WO1997039563A1

WO1997039563A1 - Method and apparatus for providing bypass networks in a telephone system

Info

Publication number: WO1997039563A1
Application number: PCT/US1997/006588
Authority: WO
Inventors: Kenneth James Hamer Hodges; Thomas Edward Sullivan, Jr.; Richard Joseph Cameron; Karen Wendy Brim; Wayne Russell Lasson; Christopher Aiuto; Joseph Lawrence Golden; Harikrishin Hirani; William Bridges Smith; Joseph P. Savage
Original assignee: Telco Systems, Inc.
Priority date: 1996-04-16
Filing date: 1997-04-16
Publication date: 1997-10-23
Also published as: AU2736297A

Abstract

A method and apparatus are provided for permitting all forms of traffic on a telephone system (10), including various forms of data traffic, to be handled without resulting in a significant degradation in service to customers (14, 16, 18, 20, 48), while facilitating the controlled growth of the telephone system (10) to handle rapidly increasing classes and levels of traffic. This is accomplished by providing one or more bypass networks (84) in such a system, with at least one class of traffic being bypassed through such bypass network (84) so as to not be passed through and utilize shared system resources. A control unit (60) for use in such a bypass network (84) architecture is also provided.

Description

METHOD AND APPARATUS FOR PROVIDING BYPASS NETWORKS IN A TFXEPHONE SYSTEM

Field of the Invention

This invention relates to telephone systems and more particularly to a method and apparatus for providmg one or more bypass networks in such a system with at least one class of traffic being bypassed through each such bypass network. The invention also relates to a control unit suitable for use in the bypass network architecture indicated above.

Background of the Invention

Current telephone systems establish a dedicated connection or circuit from a source or calling party to a destination or called party. Such connection is normally made through a local loop from the subscriber or caller to a telephone central office and through switching equipment at the telephone central office to either a local loop leading to the destination or through one or more toll switch and toll loop to another central office switch and then through a local loop to the destination. Depending on the telephone service at the caller and destination and the locations of these two parties, additional hardware may be involved in providing the connection. Once the connection is formed, which connection is determined and controlled by the telephone number dialed, the connection is maintained until one ofthe parties hangs up (i.e. goes on-hook).

The system described above requires that lines in the various networks and settings in the various switches be devoted to a particular call for the duration of the call, network capacity including the number of available switch settings, having been historically selected with certain traffic assumptions based on voice traffic characteristics so as to normally avoid overloading ofthe network. For example, depending on location, there might be four to eight times as many subscribers as there is switch capacity at a central office. Historically, such systems have worked reasonably well with the number of lines and central office capacity being incrementally increased as the number of subscribers increases and only in rare circumstances does such a network become so overloaded that it is not possible to complete a desired call, (i.e., during peak traffic periods or anomalous conditions such as on holidays or where there is a catastrophe in an area).

However, while voice calls are generally of relatively short duration, typically about three minutes, and the systems have been designed to accommodate such short duration calls, the increasing use of telephone lines to handle data traffic, and in particular the use of such lines to handle traffic on the Internet, has significantly altered the usage assumptions on which the system designs are based. In particular, when such lines are being used to handle data traffic which may be in either analog form, having been passed through a modem, or in digital form, for example using the integrated service digital network (ISDN) protocol, network usage is significantly different than for voice traffic, and these differences can render the assumptions on which the systems were designed invalid, causing potential system overloads which can result in the blockage of traffic, both voice and data, through the system. For example, if there were normally eight times as many subscribers as the maximum capacity for a central office (CO) and a little over 6% of these subscribers go on the Internet concurrently over a several hour period, which is not an unusual situation, then the CO capacity is reduced to about one for fifteen during that interval. If the Internet usage were to go to about 12.5% during the time interval, then the remaining subscribers served by the CO would be substantially blocked during that period, even though only one eighth of the subscribers were on line. More specifically, the potential problems resulting from adding significant amounts of data traffic to a telephone system designed primarily to handle voice traffic fall into the following five general categories:

1 • Origination Problems - This is basically the problem described above where users call an Internet service provider (ISP) and remain connected for extended periods of time. This can overload shared internal network resources in general, and local switches in particular, reducing the quality and grade of service for other users on the same network resources. Further, ISDN traffic (digital traffic) passing through the same lines can generate twice the traffic of a modem connection. This disrupts more traffic on the local switch and aggravates the service degradation problems.

2. High Speed Modem Problems - High speed modems attempt to transfer data at 28.8 Kb/s and higher over voice circuits which are not guaranteed to support such data rates. For example, certain types of loop lines and equipment cannot support the signal to noise ratio at the higher frequencies needed for 28.8 plus modems even though their performance is satisfactory for voice traffic. System upgrades to permit customers to take full advantage ofthe high speed modems required to for example receive video over the Net are expensive and an altemative solution is required.

3. The BRI/DLC Problem - ISDN capability or other high speed data capabilities are now designed and optimized for urban areas with high digital traffic. However, the capability to provide such service is being required at greater distances from such areas. This requires expensive system upgrades including the increased use of fiber optic cables and the need for remotely located ISDN basic rate interfaces (BRJ) or other appropriate modems. More generally, a digital loop carrier system is required which has greater flexibility. 4. The Toll Problem - Internet service providers such as America Online and

CompuServe are a unique class of subscribers in that, as they expand into increasing numbers of areas, they obtain local numbers in these areas which receive large numbers of data calls but which generate no outgoing calls. Each call that is placed to one of these numbers or destination ties up central office (and perhaps toll office) switches as well as trunk connections between the switches, and since calls to ISPs are typically long duration calls, these switches and connections are tied up for extended periods of time, degrading service for all other system users over a broad basis.

5. The Termination Problem - This problem flows from the previous problem in that each ISP number has large numbers of long duration calls terminated thereat which can significantly overload the ISP's local switch, and other circuitry involved therewith, and can in fact in some instances result in the virtual blockage of traffic for other subscribers on the same switch. While a telephone company may deal with this problem by adding capacity, this is an expensive solution, and probably only a short term solution as the transmission of data over telephone networks increases. It is also a solution which is in some ways unattractive to the telephone provider since the ISP number causing the problem generates no revenue from outgoing calls and normally generates little or no toll revenue from incoming calls. Therefore, the telephone operating company has an expensive problem to maintain quality of service for its subscribers which problem does not result in significant revenue to the operating company which could be used for solving the problem.

A problem which is related to the termination problem is that the modem banks currently being utilized by the ISPs are serviced by the ISPs rather than by the telephone company. These banks are subject to failures, and one of these modems failing can tie up the bank, preventing incoming calls from getting through. ISPs are not normally set up to perform maintenance on these modem banks and would prefer that these modem banks either be eliminated or be serviced by the telephone company. One way to eliminate modem banks is to permit digital data to be transmitted to the ISPs so that conversion by a modem bank is not required.

Another related problem caused by the ISPs is the exhaustion of available facilities. Wires for local loop transmission may be passed through conduits or the like which are already overloaded and cannot handle substantial additional lines. The buildings housing central offices may also be approaching capacity or at capacity making the addition of new switches difficult. With the uncontrolled growth currently occurring in telephone usage, it is difficult for the various companies providing telephone service to provide for required growth in an orderly fashion, particularly where real circuits rather than virtual circuits are required for transmitting digital traffic.

A need therefore exists for a method and apparatus which can be retrofitted to the existing telephone system without requiring expensive replacement of existing equipment which will solve the various problems indicated above, and in particular will permit all forms of data traffic to be handled, including ISP traffic, without resulting in any significant degradation in service to other customers including voice and data customers while facilitating the controlled growth of the telephone systems to handle rapidly increasing classes and levels of traffic.

Summary of the Invention

In accordance with the above, this invention provides a system/apparatus and method for handling at least two different classes of traffic on a network of a type normally having multiple subscribers interconnected through a telephone network which has dedicated resources, for example telephone lines, connecting each subscriber to a shared network resource, (for example a central office switch). In practicing the invention, at least one bypass network is provided for a shared resource which bypass network is adapted to handle a selected class of the traffic. At least one control unit is provided in the network ahead of a shared resource to be bypassed which unit detects traffic of a class handled by the bypass network and routes or facilitates the routing of detected traffic to the corresponding bypass network. The classes of traffic can include voice traffic and data traffic, with the class of traffic being routed to the bypass network normally being at least selected portions ofthe data traffic. Further, the data traffic may be in digital form and in analog form as the output from a modem. For some embodiments, the data traffic in analog form may be converted to digital for routing through the bypass network.

A control unit may also include a separate output port for each network to which traffic is routed by the unit, with traffic being independently applied to each output port, or the control unit may include circuitry which time slots traffic for routing to different networks. Such circuitry may be in the form of either hardware or software. A digital loop carrier may also be provided between the control unit and the shared resource, with the time slotted traffic being applied to the digital loop carrier which routes the traffic to the appropriate network. The control unit in the subscriber area may also be a local switch of a digital loop carrier.

At least one ofthe control units in the system ahead of a central office switch may contain a termination, for example a subscriber module, for each type of network input line serviced by the unit. The unit containing the termination subscriber module may be in a subscriber area, with at least some of the traffic outputted from the unit being routed through a local loop network to a central office switch. The unit in the subscriber area may include circuitry for detecting the traffic to be handled by the at least one bypass network and for routing the detected traffic to the corresponding bypass network. Alternatively, all ofthe traffic from at least some ofthe control units in a subscriber area may be routed through the local loop network, with a control unit being provided between the local loop network and the shared resource/central office switch for detecting the traffic to be handled by the at least one bypass network and for routing the detected traffic to the corresponding bypass network. For some embodiments, the bypass network receives traffic both from at least one control unit at the central office and from at least one control unit in a subscriber area. Typically, the central office detects an off-hook indication from the subscriber when the subscriber initiates traffic on the network. For preferred embodiments, the control unit is responsive to traffic being routed to a bypass network for dropping the off-hook indication for the subscriber putting such traffic on the network and also provides an appropriate response to incoming traffic from the shared network or the subscriber while the subscriber is on line through the bypass network.

The response to incoming traffic may include an answering machine which provides a predetermined output to the source ofthe incoming traffic. The answering machine may also store a message from the source ofthe incoming traffic and may permit the subscriber to access the stored message. It may also be possible for the control unit to signal the subscriber that the subscriber has a stored message. The output or response to incoming traffic may be a busy signal from the control unit or the control unit may generate a specialized signal to the appropriate central office switch indicating that the subscriber is off-hook, with traffic being routed through the bypass network.

Detection of traffic to be bypassed may be made in a number of ways including detecting and comparing on a telephone number contained with the traffic, detecting a selected analog tone, for example a modem tone, included with the traffic, or detecting at least one selected code transmitted with the traffic which is indicative of a class of traffic. Even though the traffic is detected as being of a class to be routed to the bypass network, the control unit may contain a mechanism for inhibiting the routing of selected such traffic to the bypass network. For example, the control unit may store a "cold list," with traffic having a characteristic identified by the "cold list" being inhibited from routing to the bypass network. Examples of characteristics identified on a "cold list" are provided later. The control unit may also include a mechanism for counting/ accumulating and for maintaining selected information concerning traffic routed to a bypass network. Such information may be utilized to evaluate performance ofthe system or may be subsequently collected and utilized for billing purposes.

The invention also includes a unique control unit for use in conjunction with the method and apparatus which control unit may include a termination or subscriber module for terminating each type of network input line serviced by the unit, a means for detecting traffic received at a subscriber module which is of a class handled by a bypass network and a means responsive to the detecting for facilitating the routing of traffic to the appropriate one of either the central office switch or the bypass network depending on the detected class of traffic. The control unit may include at least one circuit which is time slotted to route traffic to an appropriate one of either the central office switch or the bypass network or may contain a separate output port for routing traffic to the central office switch and to each bypass network. The control unit may also include the various elements discussed above for freeing circuits in the telephone network by providing a signal to the central office switch to drop the off-hook indication and for responding to incoming traffic to the source of the bypass traffic, as well as the inhibiting mechanism (i.e., "cold list") and the information collecting capabilities.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention as illustrated in the accompanying drawings.

In the Drawings

Fig. 1 is a block schematic diagram of an exemplary telephone system currently in use. Fig. 2 is a block schematic diagram of a portion of a telephone system in accordance with a first embodiment ofthis invention.

Fig. 3 is a block schematic diagram of a portion of a telephone system in accordance with a second embodiment ofthe invention.

Fig. 4 is a block schematic diagram of a portion of a telephone system in accordance with a third embodiment ofthe invention. Fig. 5 is a block schematic diagram of a portion of a telephone system in accordance with a fourth embodiment of the invention.

Fig. 6 is a block schematic diagram of an exemplary control unit suitable for use with the embodiments of the invention shown in Figs. 2-5. Fig. 7 is a flow diagram for the operation of a processor in an exemplary control unit.

Detailed Description

Fig. 1 illustrates an existing telephone system. This system 10 has a local loop network 12 which serves a large number of users or subscribers including telephone users (TU) 14. home or small business users (HU) 16, phone/fax users 18, and digital users (DU) 20. A telephone user 14 may for example have one or more telephones 22, each connected to the local loop through a standard telephone wall plate 24 and a subscriber line 26. Line 26 is an analog line and would typically be a copper wire, although a fiber optic line may also be utilized. An HU 16, in addition to having one or more telephones 22, also has a computer 28 connected through a modem 30 and plate 24 to analog or voice line 26. Thus, an HU subscriber site may have both voice and data on its line 26, the data being represented in analog form. Phone/fax 18 is also connected through a wall plate 24 and line 26 to the local loop and a site containing a phone/fax 18 may also have other components connected to put voice or data on line 26, including one or more phones 22 and a computer 28 operating through a modem 30. Finally, digital unit 20 has a computer 28 which is connected to a basic rate interface (BRI) 32 of an integrated service digital network (ISDN) line 34. Another type of switch digital services might also be provided, for example switched 56. Interface 32 may for example include a digital modem and data on line 34 is in digital form in accordance with the ISDN digital protocol.

The analog voice and data signals on lines 26 and the digital data signals on lines 34 are passed through the standard local loop 12 which, depending on location, may be copper wires, fiber optic lines or other medium capable of transmitting telephone signals. Traffic from local loop 12 is ultimately applied to a main distribution frame (MDF) 36, and through the MDF to a central office local switch 38. A digital cross connect cabinet (i.e., DSX-1) or other switchable equipment may be used in lieu of MDF 36 and, where an MDF is mentioned hereinafter, the reference will be understood to include such other equipment. If an incoming call is for another subscriber on the same switch, a connection will be made through the local switch 38, the MDF 36, and local loop 12 between the incoming caller, for example telephone 22 of TU 14, and the call recipient, for example telephone 22 of HU 16. This connection will remain in place for the duration of the call between the parties. Local switch 38 will also get an off-hook indication from both the originating subscriber and the receiving subscriber and will return a busy signal to any other subscriber seeking to reach the telephone numbers for either of these parties. If the number being called is outside the local switch 38, the switch sends a message through lines 40, which may for example be fiber optic lines, to toll switch 42 which then completes a circuit through lines or toll loop 40' to the local switch 38' servicing the receiving party. Local switches 38 may for example be class 5 or class 4/5 switches and toll switch 42 may for example be a class 4 toll switch. Lines 40 would typically be high speed fiber optic cable, but could be other transmission media (for example coaxial cable, radio frequency, microwave, etc.) typically used by telephone companies for long distance toll loop telephone communication.

Local switch 38' is connected through its own main distribution frame 36' to a local loop 12' to which numerous subscribers are connected. These subscribers are shown to include TUs 14' and HUs 16.' An ISP 48 is also shown as being connected to local loop 12', the ISP including a modem bank 50 connected through a local area network 52 to an ISP router 54.

The primary problem with the prior art system shown in Fig. 1 is that once a connection is established between a source and a destination, this connection is dedicated for the duration of the call. However, in order to keep equipment costs within reason, telephone companies use a statistical approach to allocating shared equipment. Thus, for example while the network typically has dedicated lines for each subscriber from the subscriber through local loop 12 and MDF 36, there are usually shared resources in the various switches 38 and 42 and toll lines/loops 40. These statistical assumptions have worked well so long as the lines were being used primarily for voice traffic where the typical call lasts for only a few minutes. However, with the increasing use of telephone systems for data applications, and in particular for accessing the Internet or World Wide Web through various ISPs, the assumptions on which the telephone system was designed are proving to be no longer valid and this is leading to problems which, if not addressed, could lead to blockage of significant portions ofthe telephone system, even for 91 1 and other emergency calls. For example, if local switches 38 are designed such that there is only 12 1/2% as much local switch capacity as there are subscribers, if ten to twelve percent ofthe subscribers are engaged in long term Internet access calls at a given time, that portion ofthe system is essentially blocked for all other classes of traffic. Even a lesser percentage of uses for long duration data accesses will overburden remaining shared resources, resulting in a significant, and generally unacceptable, degradation in the quality of service. This degradation can become particularly acute for a local switch such as switch 38' feeding an ISP 48. Since each call to the ISP's modem bank 50 would require a separate switch connection in local switch 38' and a dedicated line in local loop 12', during periods of high Internet usage, for example the evening hours, the ISP can result in significant overload for shared elements, blocking or at least significantly degrading the quality of service for all other subscribers or users on local switch. As discussed earlier, merely adding capacity to local switch 38' and local loop 12' is a short term solution which can be very expensive, will not really solve the problem, and may not be feasible in some locations where central office space and other considerations limit the ability to implement such incremental solutions. Two additional problems encountered by the system of Fig. 1 are that the long copper lines

26 which may pass through local loop 12 do not, as indicated earlier, have the signal to noise capabilities required to handle high speed modem traffic. It is therefore desirable that data traffic, particularly modem data traffic in analog form, not have to travel significant distances on such lines, but instead be converted to a form more suitable for the transmission of digital data. Further, the modem bank 50 which is part of each ISP presents a maintenance problem for the ISP which the ISPs are not well organized to handle and would prefer not to have to deal with. In particular, the failure of one or more modems in the bank can prevent proper stepping of calls through the bank and can thus effectively prevent access to the ISP. Thus, while short term, elimination of the modem banks may not be possible, a system which would facilitate the elimination of such modem banks is clearly desirable.

Therefore, in accordance with the teachings ofthis invention, a better solution to the various problems indicated above is to separate the traffic so that the existing telephone system handles only voice traffic and other traffic which it is designed to handle and is best capable of handling, with at least selected data traffic being bypassed before reaching a shared resource to a bypass network which is designed to optimally handle such class of traffic. In a simplest case, only a single bypass network is provided to handle either all data traffic or selected classes of data traffic. However, this is by no means a limitation on the invention, and as the classes of traffic being handled by telephone systems increases, and the overall volume of telephone traffic also increases, it is likely that additional bypass networks will be provided to handle the additional classes of traffic. Fig. 2 shows one embodiment of the invention wherein a plurality of control units 60 are interposed between subscribers or users 14, 16, 18, 20 and 48 and local loop 12. Each control unit 60 would be in a "subscriber area". For a large building or other facility, one or more control units 60 might be located in the facility, while for residential subscribers, a control unit 60 might be located on a telephone pole or in another suitable location on the street or in the neighborhood where the subscribers are located. Each control unit 60 performs a number of functions, including terminating the lines 26 or 34 leading into the unit, sniffing or detecting the traffic class for a particular item of traffic received at the control unit, and either routing or facilitating the routing of each item of received traffic to the appropriate network for such class of traffic. Control units 60 can also provide an on-hook indication to local switch 38 when a determination is made that traffic is to pass through a bypass network to thereby free up the local switch connection which was originally established to handle the call and can also respond or otherwise deal with incoming calls to a subscriber who is currently engaged in a call being handled through a bypass network. Accumulating and storing information for performance evaluations or billing purposes and selectively inhibiting routing of traffic of a class to be so routed by the bypass network are additional functions which can be performed by the control units. Control units for performing these various functions may assume a variety of forms, and may for example be implemented in special purpose hardware, may involve a programmed general purpose processor, or may be a hybrid of hardware and software. Fig. 6 shows one possible embodiment of a control unit 60, but it should be understood that the control unit of Fig. 6 is for purposes of illustration only, and that such control units may assume a variety of forms depending on application and design philosophy.

Referring to Fig. 6, it is seen that the control unit 60 has a plurality of separate modules or circuits which are interconnected over suitable lines or buses. For example, the unit can include one or more termination or subscriber modules 62A, 62B which terminate a particular type of input line. Thus, module 62A terminates voice lines 26 leading into control unit 60 while module 62B terminates digital ISDN basic rate interface lines 34. Additional modules 62 may be provided for terminating other types of input lines to a control unit 60. Depending on the location of a control unit 60 and on the subscribers feeding into such control unit, only a single subscriber module, such as subscriber module 62A, may be present in the control unit or additional subscriber modules may be included. Alternatively, a single subscriber module may be designed to terminate two or more types of input lines.

Traffic received at subscriber modules 62, or at least a selected portion thereof, are applied over suitable lines to signaling server 64 or other processor. This is a data processor of suitable capacity to provide a variety of control functions for the control unit. One principal function of server 64 is to sniff or detect traffic which is of a class to be routed to a bypass network. In a simplest case, server 64 stores a list of telephone numbers which are to be bypassed, for example numbers for ISPs 48, and compares the dialed or inputted telephone number of each incoming call against this list. When a match is found, server 64 generates an appropriate output to cause traffic for the matched number to be diverted to a bypass network in a manner to be discussed shortly. Alternatively, if all modem traffic is to be diverted to a bypass network, then the server 64 can be utilized to detect a modem tone and to divert corresponding traffic when such a tone is detected. Other appropriate analog tones may also be detected for purposes of routing traffic to a bypass network. Another possibility is that traffic to be routed to a bypass network could contain a particular code, either in analog or preferably in digital form, the detection of such code by server 64 resulting in the rerouting of such traffic. Depending on the nature of the traffic to be routed to a bypass network and the criteria used for performing such bypass function, other suitable criteria could be utilized and detected by server 64 for this purpose. Other functions for server 64 are discussed later.

As illustrated in Fig. 6, traffic received at subscriber modules 62 are passed through appropriate lines or buses to a data bypass switch server 66 and to a trunk module 68. These circuits also receive inputs from signaling server 64. As will be discussed in greater detail later, a control circuit 60 may operate in at least two different modes. In one mode of operation, separate output ports are provided for each of the networks to which traffic is directed. In this mode of operation, bypass switch server 66 would output bypass traffic from the control unit over lines 70 and would receive traffic from a bypass network over these lines. Similarly, in this mode of operation, trunks module 68 would output voice traffic for example to the local loop as shown in Fig. 2 over lines 72 and would receive such traffic over these lines. However, the control unit may also be designed to operate in a single port mode wherein server 66 may either not be present or may only be utilized for formatting digital traffic, for example converting modem traffic to pure digital, in a selected format such as ISDN, or to otherwise package digital data into a packet format such as ATM. In this mode, the trunks module, whether receiving all data directly from the subscriber module(s) or whether receiving data to be bypassed in some modified format from the bypass switch server, time slots the data to be routed on different networks for outputting on a single output port 72. The time slotted traffic may then be appropriately routed by other suitable circuitry based either on the time slot in which the traffic is located or on other suitable criteria known in the art.

An additional problem which a control unit deals with is the off-hook problem which results from the fact that once a call request is made by a subscriber, the system starts establishing a telephone circuit to complete the call and does not break this connection under normal conditions until the call has been completed. This would mean that a circuit involving the local loop, local switch, toll switch and/or other components of the analog voice network would be tied up even if a decision was made to pass the traffic through a bypass network. It is therefore necessary for signaling server 64, once it makes a decision that a particular call is to be routed through the bypass network, send a signal through the trunks module 68 to local switch 38 that the originating caller is on-hook, thereby terminating the call and freeing the voice network circuits.

However, once this is done, incoming traffic for the calling subscriber will not receive a busy signal at the local switch, but will be sent through to the subscriber. However, since the subscriber line is in fact busy, the incoming call must be dealt with in an appropriate way. One way to deal with this is to merely let the incoming call ring, even though the ring does not get through to the intended recipient. Another way is for signaling server 64 to generate a busy signal when an incoming call is received for a subscriber who is online through a bypass network. This can be done in a variety of ways. A third option is to provide an answering machine 74 which is triggered by signaling server 64 when a call comes in for a subscriber online through a bypass network, which answering machine can provide a busy signal, but preferably provides a prerecorded message and may permit the caller to leave a message. If the caller is permitted to leave a message on answering machine 74, then the subscriber can be permitted to access such messages at a later time by dialing an appropriate number and inputting an appropriate extension or access code. For a preferred embodiment, signaling server 64 provides an indication to the subscriber through the appropriate subscriber module, indicating that there is a message for the subscriber. In the simplest case, this indication would be in the form of a telephone call placed to the subscriber when the subscriber goes offline which causes a suitable message or icon to appear on the screen of the user's computer or causes some other suitable indication, for example a light or tone on the user's phone or even a ringing ofthe user's phone with a recorded message when the user picks up the phone advising that there is a message waiting. A more sophisticated approach would be for the indication to be either piggy-backed on a message sent to the subscriber from for example an ISP or preferably a message inserted onto a line leading to the subscriber when there is no other traffic on the line involving the subscriber, which message causes a suitable message or icon on the user's screen advising that there is a message waiting, and possibly even some information such as telephone number of the calling party. It is noted that when calls are routed through a bypass network, the recipient of the call is also off-hook, but this is not reflected at the local switch for the recipient. Therefore, the signaling server for the control unit serving such recipient must deal with the same off-hook problem dealt with by the control unit for the calling party. The one exception would be calls placed to an ISP which can handle multiple incoming calls through its modem bank. When the unit 60 is operating with both output ports 70 and 72, signaling server 64 normally controls module 66 and 68 so that an output appears on only one such port. The incoming traffic, for example the dialed telephone number, may be stored in both modules until signaling server 64 makes a decision as to which port the traffic is to be outputted on or the incoming traffic may be broadcast from both ports until the decision is made, with the unused port then merely being shut down.

If desired, signaling server 64 may also be programmed to provide a variety of additional functions. For example, a "cold list" of subscribers generating a class of traffic which would normally be routed to the bypass network may be stored at the signaling server, which lists may include fields which for example indicate if the subscriber has paid his bill or what types of services the subscriber is eligible to use or receive. If for some reason the subscriber is not eligible to transmit the class of traffic being sent through the bypass network, the signaling server can detect this from the "cold list" and can prevent or inhibit further transmission of the subscriber's traffic. The control unit may then return a message to the subscriber advising ofthe problem or take other appropriate action. The "cold list" may also contain information concerning the destination ofthe traffic. For example, if the destination is an IAP which is using a modem bank, it may not be possible to route the traffic to a digital bypass network, and if may therefore be necessary to route such traffic either though the normal analog network or through an analog bypass network. Conversely, if the "cold list" indicates that an IAP is set up to receive digital data, the traffic may be routed to the IAP through a digital bypass network. The signaling server may also be programmed to collect selected information concerning traffic being routed to one or more bypass networks, either for purposes of performance evaluation of the system, for billing purposes, or for other reasons. Suitable counters may, for example, be provided for this purpose. Where the information is being accumulated for billing purposes, the control unit may be periodically interrogated by a central office switch of other suitable equipment to retrieve the accumulated information for billing purposes.

Fig. 7 is a flow diagram for the operation ofthe illustrative signaling server 64. Referring to this figure, during step 80 the server monitors the subscriber channels. In particular, during step 82, the server makes a determination as to whether the line from a subscriber is off- hook. Nothing happens if there is a "No" output during step 82. If there if there is a "Yes" output during step 82, the operations proceeds to step 84 to determine if the line has already been placed in a "sniffer queue," thereby indicating that the line is already being monitored. A "No" output during step 84 results in the operation proceeding to step 86 to place the line in the "sniffer queue."

If a "Yes^"" output is obtained during step 84, the operation proceeds to step 88 to determined if the entire telephone number has been entered. If a "No" output is obtained during step 88, the operation proceeds to step 90 to store the portion ofthe number which has been added and to exit. When during step 88 it is determined that the entire telephone number has been entered, the operation proceeds to step 92 to remove the line from the "sniffer queue" and to determine if the number entered is a "hot list" number. For example, if ISP numbers are stored and matched on. a "Yes" output will be obtained during step 92 if the number called is an ISP number. As discussed earlier, step 92 may be performed in other ways. For example, instead of detecting a "hot list' number, the signaling server may detect a modem or other analog tone as an indication that a particular transaction or traffic item is to be routed to a bypass network or may detect some other code included with the message. If a "No" output is obtained during step 92, the operation proceeds to step 94 to route the call to central office or local switch 38. This can be done in any of the ways previously discussed.

If a "Yes^"* output is obtained during step 92, the operation proceeds to step 96 to determined if either the subscriber or the called party is on a "cold list." If a "Yes" output is obtained during step 96 the operation proceeds to step 98 to determine if the call should be routed to the central office switch. Depending on the nature of the entry in the "cold list," a "Yes" output may be obtained during step 98 causing the operation to proceed to step 94. If a "No" output is obtained during step 98, a variety of things may happen. In Fig. 7, this output is shown as leading to step 100 where a message is returned to the subscriber advising that the call cannot be completed and the call is terminated. However, depending on the nature ofthe entry in the "cold list," the message might be routed to another bypass network or treated in some other way.

If there is a "No" output during step 96, the operation proceeds to step 102 to route the call to the appropriate bypass network. The operation may also proceed to step 104 to perform a selected count on the call for performance evaluation, billing, or other purposes. A step 106 may also be performed to determine is there a bit in a control field for the call. Such bit may for example indicate that the message is to be received in analog or digital form, or perform some other control function. If there is a "Yes" output during step 106, the operation proceeds to step 108 to perform the selected control function. Alternatively, steps 106 and 108 may be performed after step 96 and be part ofthe process for determining the bypass network to which the call is routed. Finally, for reasons previously discussed, a step 1 10 is performed to send an on-hook indication to the local switch 38. This step may be performed during step 102 or at any time after a "No" output is obtained during step 96.

Referring again to Fig. 2, each control unit 60 is shown as having an output line 72 to local loop 12. Traffic routed to local loop 12 would be handled in substantially the same manner as such traffic for the embodiment of Fig. 1 , with only the distribution frame 36 and local switch 38 of such network being shown in Fig. 2. However, it should be understood that the other portions of the standard telephone network shown in Fig. 1 would also be present for the embodiment of Fig. 2. For reasons discussed previously, traffic routed by control unit 60 to local loop 12 would be. for preferred embodiments, voice traffic and perhaps certain forms of other analog traffic such as some forms of modem traffic. Each control unit 60 also has an output connected to a data bypass switch 78 and a connection to a bypass switch 80. Data bypass switch 78 may for example be a frame relay or other switch capable of either packetizing or placing data, preferably digital data, on a packet bypass network 82 which may for example be an ATM network, X.25 packet network, frame relay SMDS network, or the like. Such networks have reduced bandwidth requirements because a permanent connection is not maintained between a calling and receiving location, but instead, each packet of data contains an address to which the packet is routed through a virtual circuit formed only for such packet. Such arrangement is particularly well suited for sending and receiving information to an ISP where many items of traffic may be routed to a single destination. Data bypass switches 78' are provided at other sites in the system for receiving data from network 82 and routing such traffic to an appropriate user or for receiving data from a user through an appropriate control unit 60 and routing such traffic through network 82.

Bypass switch 80 may for example handle modem data (i.e. digital data in analog form) and may route this data through a bypass network 84. This arrangement may be suitable for handling calls from multiple subscribers to an ISP which is local and which operates with a modem bank 50 so that the expense of converting this traffic to digital form and packetizing it cannot be justified. However, the network 84 permits this traffic to bypass local loop 12 and local switch 38, thereby alleviating the origination problem, toll problem and termination problem discussed above in connection with ISPs. Bypass network 84 could for example connect multiple subscribers to ISP 48, including the HU and DU subscribers 16 and 24 shown for the same local loop, or could be utilized to connect the subscribers to an ISP on another local loop. Additional bypass switches 80' are present at various locations to put data on network 84 or to receive data from this network. Suitable control units 60 would be provided for each switch 78' and 80'.

One particular advantage of the embodiment shown in Fig. 2 is that, with the control units 60 located in subscriber areas, the length of relatively low quality lines 26 is minimized and high speed modem traffic thus is transmitted primarily through a bypass network which is specifically designed for such traffic and permits such traffic to be transmitted at any desired data rate. This is particularly advantageous in that if service is required for a new class of particularly high speed modems, the entire telephone system does not have to be upgraded to handle such traffic, but such traffic can be handled by merely provided for example an additional port or module in appropriate control units to handle such inputs and a bypass network for such traffic. This system is thus highly flexible and scalable for new classes of traffic and new services, as well as handling various types of traffic increases without resulting in the system capabilities of becoming exhausted. Another advantage is that everything that is done in this system is completely transparent to the user or subscriber, and upgrades at the user facility are not required (except possibly for the installation of a control unit) in order to handle the various types of data traffic. This contrasts with some existing technologies where for example a special ISDN line must be brought into the subscriber in order to provide this class of service. Further, since a bypass network 82 or 84 leading to an ISP may be a digital network, it is possible for modem banks 50 to be eliminated, eliminating the maintenance overhead introduced by these banks and improving system performance. Another advantage ofthis system is that the control units do not have to provide special functions or services to subscriber that are normally provided by a local switch since the control unit is transparent for voice or other types of services not bypassed and the local switch 38 can therefore continue to provide such functions. The control unit need therefore only provide services for bypassed traffic

Fig. 3 shows a system which differs from that shown in Fig. 2 in that the control units 60 in the subscriber area merely terminate incoming traffic and direct it to local loop 12. Traffic on local loop 12 passes through a main distribution frame 36 to a control unit 60' which unit may, for example, not require the subscriber modules 62. Control unit 60' detects traffic to be diverted to a bypass network in the manner previously described in conjunction with Figs. 2 and 6 and directs such traffic through data bypass switch 78 to bypass network 82. Additional bypass networks such as bypass network 84 may be provided and/or such bypass network may be utilized in lieu of the bypass network 82. Control unit 60' routes traffic which is not to be bypassed to local switch 38. The embodiment of Fig. 3 is advantageous in that it simplifies the circuitry required at multiple subscriber sites and is therefore simpler to initially implement and less expensive. Initial installation might therefore be of this type. However, this embodiment does not solve the high speed modem problem discussed earlier and, at least for this reason, an embodiment more along the lines of Fig. 2 may ultimately be preferred. However, since an ISP can be connected directly to the bypass network, rather than through its own local switch, this embodiment can relieve the termination problem discussed above and may therefore be useful. Fig. 4 shows an embodiment which differs from that of Fig. 3 in that instead of all of the control units at the subscriber area being connected to the data bypass switch 78 through the control unit 60' at the local switch end of the local loop, one of the control units 60A is shown as being connected directly to bypass switch 78. Thus, for example, control unit 60A could be receiving inputs over both audio lines 26 and digital lines 34, and the signals on the digital lines could be sent directly from a port 70 to bypass switch 78, while the remaining traffic goes through lines 72 to the local loop. Except for this difference, the system of Fig. 4 operates in substantially the same manner as the embodiment of Fig. 3.

Fig. 5 shows still another embodiment of the invention wherein the output traffic from control unit 60 is on a line 72 which is preferably a time shared fiber optic line, with both digital or analog traffic to be bypassed and voice traffic to be routed to local switch 38 appearing on fiber 72. This mixture of bypassed and non-bypassed traffic sharing a common transmission medium, usually a time shared or multiplexed medium, is applied to a central office terminal or to a host digital terminal 90 which is part of a digital loop carrier such as those available from DSC, AT&T, Fujitsu and others. Terminal 90 is capable of separating the time shared data applied thereto, routing the data to be bypassed through data bypass switch 78 to bypass network 82 and routing the voice and other traffic to pass through local switch 38 to this switch. Again, except as indicated above, the system of Fig. 5 operates in the same manner previously described for the earlier embodiments. Digital loop carrier systems may also include a remote switch located at a subscriber area in the same way for example as a control units 60 shown in Fig. 2. A system has therefore been presented which may be retrofitted to existing telephone systems without requiring major revision of such systems and which permits traffic which such existing systems are not designed to handle to be bypassed to networks more suitable for handling such traffic, thereby permitting telephone systems to continue to provide acceptable levels of voice service, while also handling the ever increasing volume of data traffic passing through these lines. The system also provides an efficient way to handle new classes of service without requiring upgrading of an entire telephone system. The system provides a mechanism for recording messages received by a user during the long periods of time that users are online and, for some embodiments, permits a user to be advised of waiting messages while the user is online so that the user may determine whether to get offline and return calls. The high speed modem problem is also efficiently dealt with by the system.

While the invention has been particularly shown and described above with reference to preferred embodiments, it will be apparent to those skilled in the art that these embodiments are for purposes of illustration only and that various modifications and enhancements are possible in these embodiments, including those described above, while still remaining within the spirit and scope of the invention. Thus, the invention is only to be limited by the following claims.

Claims

1. A system for handling at least two different classes of traffic on a network of a type normally having multiple subscribers interconnected through a telephone network having dedicated resources connecting each subscriber to a shared network resource, the system comprising: at least one bypass network for a said shared resource, which bypass network is adapted to handle a selected class of traffic; and at least one control unit in the network ahead of each shared resource to be bypassed, which detects traffic of a class handled by a said bypass network and facilitates the routing of detected traffic to the corresponding bypass network.

2. A system as claimed in claim 1 wherein the classes of traffic include voice traffic and data traffic, and wherein the class of data routed to the bypass network is at least a selected portion ofthe data traffic.

3. A system as claimed in claim 2 wherein said data traffic is in digital form and in analog form, and including means for converting the data traffic in analog to digital for routing through the bypass network.

4. A system as claimed in claim 1 wherein the control unit includes a separate output port for each network to which traffic is routed by the unit, with traffic independently applied to the output ports.

5. A system as claimed in claim 1 wherein the control unit includes circuitry which time slots traffic for routing to different networks.

6. A system as claimed in claim 5 including a digital loop carrier between the control unit and the shared resource, the time slotted traffic being applied to the digital loop carrier which routes the traffic to the appropriate network.

7. A system as claimed in claim 1 wherein at least one of said units contains a subscriber module for each type of network input line serviced by the unit.

8. A system as claimed in claim 7 wherein the unit containing the subscriber module is in a subscriber area, at least some ofthe traffic outputted from said unit being routed through a local loop network to a said shared resource.

9. A system as claimed in claim 8 wherein the unit in the subscriber area also includes circuitry for detecting the traffic to be handled by the at least one bypass network and for routing the detected traffic to the corresponding bypass network.

10. A system as claimed in claim 8 wherein all the traffic from at least some ofthe control units in a subscriber area is routed through said local loop network; and including a control unit between the local loop network and a central office switch which is a said shared resource for detecting the traffic to be handled by the at least one bypass network and for routing the detected traffic to the corresponding bypass network.

1 1. A system as claimed in claim 10 wherein the bypass network receives traffic both from at least one control unit at the central office and from at least one control unit in a subscriber area.

12. A system as claimed in claim 8 wherein a said control unit in a subscriber area is a local switch of a digital loop carrier.

13. A system as claimed in claim 1 wherein the shared resource is a central office switch.

14. A system as claimed in claim 1 wherein a said shared resource is a central office normally providing an off-hook indication for a subscriber when the subscriber puts traffic on the network, and wherein a said control unit includes means responsive to traffic being routed to a said bypass network for dropping the off-hook indication for the subscriber putting such traffic on the network, and means for responding to incoming traffic for the subscriber while the subscriber is on-line through the bypass network.

15. A system as claimed in claim 14 wherein the means for responding includes an answering machine which provides a predetermined output to the source of incoming traffic.

16. A system as claimed in claim 15 wherein the answering machine includes means for storing a message from the source ofthe incoming traffic, and means for permitting the subscriber to access the stored message.

17. A system as claimed in claim 16 wherein the control unit includes means for signaling the subscriber that the subscriber has a stored message.

18. A system as claimed in claim 15 wherein the predetermined output is a busy signal.

19. A system as claimed in claim 14 wherein the means for responding includes means for generating a specialized signal to the said central office switch indicating that the subscriber is off- hook with traffic being routed through the said bypass network.

20. A system as claimed in claim 1 wherein said control unit includes means for inhibiting the routing of selected traffic ofthe class to be handled by a said bypass network from being routed to the bypass network.

21. A system as claimed in claim 20 wherein said means for inhibiting includes a cold list stored at said control unit, said selected traffic being traffic having a characteristic identified on said cold list.

22. A system as claimed in claim 1 wherein said control unit includes means for accumulating and maintaining selected information concerning traffic routed to a bypass network.

23. A method for handling at least two different classes of traffic on a network of a type normally having multiple subscribers interconnected through a telephone network having dedicated resources connecting each subscriber to a shared network resource, the method comprising the steps of:

(a) providing at least one bypass network for a said shared resource, which is adapted to handle a selected class of traffic; (b) detecting, at a point in the network ahead ofthe shared resource, traffic which is of a class to be handled by a said bypass network; and

(c) routing detected traffic to the corresponding bypass network.

24. A method as claimed in claim 23 wherein the classes of traffic include voice traffic and data traffic, and wherein the class of traffic routed to the bypass network is at least a selected portion of the data traffic.

25. A method as claimed in claim 24 wherein said data traffic is in digital form and in analog form, and including the step of converting the data traffic in analog to digital for routing through the bypass network.

26. A method as claimed in claim 23 wherein step (b) is performed by detecting selected telephone numbers.

27. A method as claimed in claim 23 wherein step (b) is performed by detecting a modem sound.

28. A method as claimed in claim 23 wherein step (b) is performed by detecting at least one selected code indicative of a class of traffic.

29. A method as claimed in claim 23 wherein a said shared resource is a central office normally providing an off-hook indication for a subscriber when the subscriber puts traffic on the network; and including the steps performed in response to traffic being routed to a said bypass network of dropping the off-hook indication for the subscriber putting such traffic on the network, and responding in a predetermined way to incoming traffic for the subscriber while the subscriber is on¬ line through the bypass network.

30. A method as claimed in claim 29 including the steps of storing a message from the source of the incoming traffic, and permitting the subscriber to access the stored message.

31. A method as claimed in claim 23 including the step of inhibiting the routing of selected traffic ofthe class to be handled by a said bypass network from being routed to the bypass network.

32. A method as claimed in claim 23 including the step of accumulating and maintaining selected information concerning traffic routed to a bypass network.

33. A control unit for use in a system for handling at least two different classes of traffic on a network of a type normally having multiple subscribers interconnected through a telephone network having dedicated resources connecting each subscriber to a shared network resource, and having at least one bypass network for said shared network resource, which bypass network is adapted to handle a selected class of traffic, the control unit comprising: termination for each type of network input line serviced by the unit; means for detecting traffic received at a said terminations which is of a class handled by a said bypass network; and means responsive to the means for detecting for facilitating the routing of traffic to an appropriate one ofthe shared network resource and a said bypass network depending on the detected class for the traffic.

34. A control unit as claimed in claim 33 wherein the means for detecting includes a processor which detects a said class of traffic to be handled by a said bypass network by detecting and comparing on a telephone number contained with the traffic.

35. A control unit as claimed in claim 33 wherein the means for detecting includes a processor which detects a said class of traffic to be handled by a said bypass network by detecting a selected analog tone included with the traffic.

36. A control unit as claimed in claim 33 wherein the means for detecting includes a processor which detects a said class of traffic to be handled by a said bypass network by detecting a selected code transmitted with the traffic.

37. A control unit as claimed in claim 33 wherein the means for routing includes at least one circuit which is time slotted to route traffic to an appropriate one ofthe shared network resource and a said bypass network.

38. A control unit as claimed in claim 33 wherein said means for routing includes a separate port for routing traffic to the central office switch and to each said bypass network.

39. A control unit as claimed in claim 33 wherein a said shared network resource normally provides an off-hook indication for a subscriber when the subscriber puts traffic on the network, and wherein a said control unit includes means responsive to traffic being routed to a said bypass network for dropping the off-hook indication for the subscriber putting such traffic on the network, and means for responding to incoming traffic for the subscriber while the subscriber is on-line through the bypass network.

40. A control unit as claimed in claim 39 wherein the means for responding includes an answering machine which provides a predetermined output to the source of incoming traffic.

41. A control unit as claimed in claim 40 wherein the answering machine includes means for storing a message from the source of the incoming traffic, and means for permitting the subscriber to access the stored message.

42. A control unit as claimed in claim 41 wherein the control unit includes means for signaling the subscriber that the subscriber has a stored message.

43. A control unit as claimed in claim 39 wherein the means for responding includes means for generating a specialized signal to the said shared network resource indicating that the subscriber is off-hook with traffic being routed through the said bypass network.

44. A control unit as claimed in claim 33 including means for inhibiting the routing of selected traffic ofthe class to be handled by a said bypass network from being routed to the bypass network.

45. A control unit as claimed in claim 44 wherein said means for inhibiting includes a cold list stored at said control unit said selected traffic being traffic having a characteristic identified on said cold list.

46. A control unit as claimed in claim 33 including means for accumulating and maintaining selected information concerning traffic routed to a bypass network.