Wide-band telecommunication system

The subject of the invention is a method and system for controlling a telecommunications network, and a telecommunications signaling processor, especially for broadband systems that use narrowband circuit switching nodes with different calling capacities.

Known circuit switching nodes provide the backbone for many current telecommunications networks. These switching nodes process the call signaling and extend the call connection to the recipient. They have been expanded to provide features such as caller confirmation, number display, routing, call control and invoice load. Switches are also used to perform various services, for example, they implement calling cards, calling numbers beginning with 800, sending voice messages and services of a given class.

The asynchronous ATM transfer mode technique currently being developed to provide broadband switching capacity for telecommunications connections that are required for telecommunications services. Some ATM systems use ATM cross connections to provide virtual connections, but devices with cross connections do not have the ability to process signaling used by telecommunications networks to set up and disconnect connections. Therefore, ATM cross connections cannot create connections based on a call by a call. As a result, connections through cross-connection systems that form a relatively rigid switching structure must be pre-provided.

Due to this limitation, cross-connection systems are mainly used to provide dedicated connections such as fixed PVC virtual channels and fixed PVP virtual paths. However, they do not provide ATM switching based on call-to-call, which is required when providing switched SVC virtual channels or switched SVP virtual paths.

ATM switch nodes are also used to provide fixed PVC virtual channels and fixed PVP virtual paths that are not determined on the basis of a call by a call, so the ATM switch node does not need to use connection or signaling capability. ATM switching nodes require both the use of signaling capacity and connection service capability to provide fixed SVC virtual channels and fixed SVP virtual paths. In order to obtain the switching of the virtual connection based on call-to-call, the ATM switching nodes are expanded to support connections in response to signaling to provide a virtual connection for each connection. However, these systems are very complex, and ATM switches need to support large numbers of connections and saved transient services from existing networks. An example is the ATM switch that handles large numbers of traditional POTS telephone network, 800 and VPN connections.

Known ATM multiplexers, capable of converting other formats of traffic into ATM format, are ATM cooperating multiplexers. The multiplexers have been expanded to convert traffic into ATM cells and multiply the cells for transmission over the network

187 643

ATM. These ATM multiplexers are not used to make virtual connections based on call-by-call.

The method according to the invention consists in receiving the first signaling message in the signaling processor, in which the first signaling message is processed for the selection of the virtual identifier and the connection, the first control message is generated and sent from the signaling processor identifying the virtual identifier, it is generated and sent a second control message from the signaling processor identifies the connection, a second signaling message is generated and sent from the signaling processor identifying the connection, the first control message is received in the first cooperating multiplexer in which the narrowband user transmissions are converted to asynchronous user transmissions with the virtual identifier and asynchronous user transmissions are sent based on the first control message, a second control message and asynchronous user transmissions are received in a second cooperating multiplexer in which the asynchronous user transmissions are converted to narrowband user transmissions and the narrowband user transmissions are transmitted through a connection based on a second control message, the narrowband user transmissions from the connection and the second signaling message are received at the narrowband switch and the narrowband switch is processing the user's narrowband based on the second signaling message.

Preferably, a third signaling message is generated and sent from the narrowband switch and the narrowband user transmissions are sent from the narrowband switch, a third signaling message is received in the signaling processor in which the third signaling message is processed to select a different virtual identifier, a third control message is generated and sent from a signaling processor identifying another virtual identifier, a third control message and narrowband user transmissions are received in the second cooperating multiplexer and in this second cooperating multiplexer the narrowband user transmissions are processed into other asynchronous user transmissions with a different virtual identifier and these other asynchronous user transmissions are transmitted based on the third control message.

Preferably, when processing the third signaling message to select another virtual identifier, the destination code in the third signaling message is processed.

Preferably, when processing the first signaling message to select a virtual identifier, the destination code in the first signaling message is processed.

Preferably, when processing the first signaling message to select a virtual identifier, the virtual identifier is selected based on access and load information for the narrowband switch.

Preferably, start address messages are used as the first signaling message and the second signaling message.

The system according to the invention comprises a signaling processor for receiving and processing a first signaling message for selecting a virtual identifier and a connection on whose outputs there is a first control message identifying a virtual identifier, a second control message identifying a connection and a second signaling message identifying a connection, to the output of the first control message and narrowband user transmissions of the signaling processor is connected via the first link the first cooperating multiplexer for processing narrowband user transmissions into asynchronous user transmissions with a virtual identifier, to the output of the second control message and asynchronous user transmissions of the signaling processor is connected via a second link a cooperative multiplexer for processing asynchronous user transmissions into narrowband user transmissions and to the output of the second signaling and narrowband messages

187 643 user transmissions are connected via a third narrowband switch.

Preferably, the narrowband switch is adapted to generate and send a third signaling message over a third link and to send a narrowband user transmissions, the signaling processor is adapted to receive a third signaling message over a third link, to process a third signaling message to select another virtual identifier, and to generate and send third control message, identifying another virtual identifier, and the second cooperating multiplexer is adapted to receive the third control message over the second link and to receive the user's narrowband transmissions, to process the user's narrowband transmissions into other asynchronous user transmissions with another virtual identifier based on the third control message and to send other asynchronous user transmission.

Preferably, the signaling processor is adapted to process the destination code in the third signaling message to select another virtual identifier.

Preferably, the signaling processor is adapted to process the destination code in the first signaling message for selecting a virtual identifier.

Preferably, the signaling processor is adapted to process access and load information for a narrowband communication node to select a virtual identifier.

Preferably, the system according to the invention has an input of a first signaling message and an output of a second signaling message being start address messages.

The telecommunications signaling processor according to the invention comprises a first interface for receiving a first signaling message and transmitting a second signaling message, connected to a second interface for transmitting a first control message and a second control message, via a processor for processing the first signaling message for selecting a virtual identifier and connecting to a narrowband switch . for generating the first identifying control message and the second identifying control message and the second identifying signaling message.

Preferably, the first interface has a third signaling message receiving input, the second interface has a third control message output and the processor is adapted to process the third signaling message to select a different virtual identifier and to generate a third control message identifying the different virtual identifier.

Preferably, the processor according to the invention comprises a connection processor for processing the destination code in the third signaling message for selecting a different virtual identifier.

Preferably, the processor according to the invention comprises a connection processor for processing the destination code in the first signaling message for selecting the virtual identifier.

Preferably, the processor according to the invention comprises a connection processor for processing access and load information for a narrowband switch for selecting a virtual identifier.

Preferably, in the processor of the invention, the first signaling message and the second signaling message are start address messages.

An advantage of the invention is to provide efficient methods and systems that combine the capabilities of broadband components with the capabilities of known switching nodes that provide ATM virtual connections based on call by calling, supporting many of the services currently provided by switching nodes.

187 643

The subject of the invention is shown in the embodiments in the drawing. on which. Figure 1 is a block diagram of a telecommunications network control system according to the invention. Figure 2 is a block diagram of a signaling telecommunications processor according to the invention and Figure 3 is a block diagram of a system according to the invention.

Figure 1 shows a version of the invention. The term "connection" refers to transmission bearers used for carrying traffic and the term "link" refers to transmission bearers used for carrying signaling or control messages. In Fig. 1, the connections are marked with solid lines and the links are marked with dashed lines. Users 100 and 102 are connected to broadband system 104 via connections 150 and 151. Users 100 and 102 are also connected to broadband system 104 via links 160 and 161. Users 100 and 102 can be any object. which supplies telecommunication traffic to broadband system 104 or which receives traffic from broadband system 104. Some examples are telecommunications switch or basic CDE station equipment. Connections 150 and 151 represent any connection. which can be used by users 100 and 102 to access broadband 104. Examples include: DS3 connections. DS1. DS0. ISDN. E3. E1. E0. SDH. SONNET. Cellular and PCS. Links 160 and 161 represent any signaling link. which can be used between users 100 and 102 and broadband system 104. Examples include signaling system # 7 SS7. CT, ISDN. CP / IP and UDP / IP.

Broadband 104 includes a cooperative multiplexer (mux) 110. Cooperative multiplexer (mux) 112. Cooperative multiplexer (mux) 114. ATM 120 cross-connection. Narrow band switch 130 and 132 and signaling processor 140. Broadband 104 also includes connections 152-156 and links 162-166. Cross connection 120 is connected to multiplexers 110. 112 and 114 via connections 152. 153 and 154. Multiplexer 112 is connected to switch 132 via connection 155. And multiplexer 114 is connected to switch 130 via connection 156. Multiplexer 114 is connected to user 100 via connection 150. And multiplexer 112 is connected to user 102 via connection 151. Connections 152 -154 are ATM connections preferably carried over the SONET network. Connections 155 and 156 are narrowband connections similar to connections 150 and 151. Preferably, connections 155 and 156 are connections DS3 and DS1 with inserted DS0.

The signaling processor 140 is connected to multiplexer 110 via link 162. to multiplexer 112 via link 163. to switch 132 through link 164. to multiplexer 114 via link 165 and to switch 130 through link 166. The signaling processor is connected to users 100 and 102 on links 160 and 161. A person skilled in the art is aware of this. that STP can be used to exchange signaling instead of direct links. Links 160.16. 164 and 166 are conventional signaling links. for example, SS7. ISDN or CT. Links 162. 163 and 165 are any links. which carry control messages. with examples being SS7 links. UDP / IP in an Ethernet network or bus system using a conventional protocol. Usually, switching nodes and multiplexers are connected to the network management system. which for simplicity is not shown.

The ATM 120 cross-connection is a conventional device. which provides multiple ATM virtual connections between multiplexers. Typically, a virtual connection would use DS1 for transmission. DS3 or SONET. Virtual connections are usually determined by the virtual path identifier / VPI / VCI virtual channel identifier. These VPI / VCI are provided from the multiplexer to the multiplexer. but the cross connection does not have to be controlled on the basis of the call by the call. An example of a cross-connection is the NEC 20 model. Specialists in this field are familiar with. that multiple cross connections could be used in this way. but for simplicity only a single cross connection is shown. Either a single cross connection or multiple cross connections are discussed as a cross connection system.

Multiplexers 110, 112 and 114 are adapted to cooperate. i.e. service. traffic between formats. ATM and non ATM in response to control messages from the processor

187 643 signaling 140. Usually this interaction causes the interaction of individual DS0 with individual VPI / VCI according to messages from the IM signaling processor

A detailed description of the multiplexers is given below.

Narrowband switching nodes 130 and 132 are conventional circuit switching nodes. These switching nodes handle and connect calls. They usually combine input DS0 with output DS0. They often perform various tasks, including approval, shielding, routing and echo control. These switching nodes can also be adapted to provide special services. Examples of special services are: calling cards, class services, voice-activated calling and voice messaging, virtual private network, assisted / amplified impaired hearing, operator services and intelligent network call routing (portable local number, person / terminal mobility, free call ).

Signaling processor 140 is adapted to receive and process signaling to select a narrowband switch and connections to a selected switch. This switch selection can be based on various criteria. Some examples are: reachable switch node access, current switch node load, switch node service capacity or area served by the switch. Usually the connections would be VPI / VCI and DS0. The signaling processor 140 is capable of providing control messages to the multiplexers for making connections. Signaling processor 140 is also able to exchange signaling with switching nodes to facilitate call handling. If desired, the signaling processor 140 may also exchange signaling with users to facilitate calling. A detailed description of the signaling processor 140 is given below.

In one embodiment, the invention works as follows for a call from user 100 to user 102. In this embodiment, the signaling processor 140 is transparent to users and to narrowband switches. Users and narrowband switching nodes try to interact as if they were in a typical network scenario. In the context of the invention, the signaling is "interrupted" and processed by the signaling processor 140. Connections are "broken" and extended by multiplexers.

User 100 will determine the call connection in connection 150 with multiplexer 110. Typically, this is DS0 inserted into DS3. User 100 will also send a call setting message to the signaling processor 140. This is usually an IAM start address message. Signaling processor 140 will process the IAM to select a switch for connection handling, will select connections for that node. For example, if switch 130 is selected, an ATM connection would be selected initially provided through a cross connection 154 from multiplexer 110 to multiplexer 114 via connections 152 and 154. In addition, the connection to switch 130 would be selected in connection 156. For a standard VPI / VCI and DS0 would be selected by the signaling processor 140.

Signaling processor 140 would send an IAM start address message to switch 130 via link 166. IAM would contain information used to handle the connection, such as dialed number and DS0 input. The signaling processor would send the control message to multiplexer 110 via link 162. The control message would instruct the multiplexer 110 to process DS0 in connection 150 with the selected VPI / VCI in connection 152. The signaling processor would send the control message to multiplexer 114 via link 165. The control message would instruct the multiplexer 114 to process the selected VPI / VCI in connection 154 with the selected DS0 in connection 156. As a result, the call path from user 100 to switch 130 would be determined by multiplexer 110 , cross connection 120 and multiplexer 114.

Switch 130 would process the call and select the route for the call. The switch would connect the input DS0 in connection 156 with another DS0 in connection 156. Switch 130 would also send IAM indicating the destination to the call. In this example, the recipient selected by switch 130 would be a user. IAM from node 184 643 of switch 130 would be routed to signaling processor 140. Signaling processor 140 could read the destination point code including IAM to determine the recipient (user 102) selected by the switch for the call. The signaling processor 140 would choose VPI / VCI from multiplexer 114 to the multiplexer serving the recipient of multiplexer 112. The signaling processor 140 would also choose DS0 in connection 151 between multiplexer 12 and user 102.

The signaling processor 140 would send the control message to multiplexer 114 via link 165. The control message would instruct the multiplexer 114 to process DS0 in connection 156 with the selected VPI / VCI in connection 154. The signaling processor 140 would send the control message to multiplexer 112 via link 163. The control message would instruct multiplexer 112 for processing the selected VPI / VCI in connection 153 with the selected DS0 in connection 151.

Signaling processor 140 could send a signaling message to user 102 to facilitate call termination.

As a result, the call path from switch 130 to user 102 would be determined by multiplexer 114, cross connection 120 and multiplexer 112. By combining these two call paths, the connection from user 100 to user 102 is established by broadband system 104. Preferably this is achieved by broadband ATM connections, but without the need for an ATM switch or call control by calling for an ATM cross-connection. Multiplexers and cross connections provide ATM connections selected by the signaling processor based on call-by-call. The signaling processor makes these choices based on the support of narrowband switch connections. The narrowband switch is also capable of providing special features for the call.

Preferably, only one narrowband switch was required in system 104. Due to the fact that broadband ATM transmission is available, the location of this switch is relatively independent. In the system 104 any switch can be used to service the connection. The ATM system provides a connection from the point of origin to the switch and from the switch to the destination. This means that narrowband switching nodes can be selected based on load and availability. A narrowband switch could also be deprived of service simply by instructing the signaling processor not to select it.

Signaling processor

The signaling processor is usually separated from the multiplexers, but those skilled in the art are aware that they could be built together and incorporated into a bus system instead of being attached via a data link or signaling. The signaling processor may support a single multiplexer or multiple multiplexers. The signaling processor is composed of computer hardware and software. Those skilled in the art are aware that there are various pieces of computer equipment that can support the requirements of the invention. One example of such computer hardware is FT-Sparc from Integrated Micro Products PLC. FT-Sparc could use the Solaris operating system. Any data storage requirements could be met by conventional database software systems.

Figure 2 shows an example of a signaling processor, but any processor that meets the requirements of the invention would be sufficient. As shown in Figure 2, the signaling processor 240 includes functional blocks composed of an SS7 interface 242, a multiplexer interface 244 and a connection processor 246. These functional blocks have interrelationships which are indicated and discussed below. The SS7 242 interface receives and transmits SS7 signaling over link 261. The multiplexer interface 244 exchanges control messages with the multiplexers via link 263. The connection processor 246 exchanges network management information with network management systems via link 263.

The SS7 242 interface is adapted to receive and send SS7 messages. The SS7 242 interface contains functional circuits of the MTP message transfer part for MTP levels 1, 2 and 3. MTP 1 defines the physical and electrical requirements of the signaling link.

187 643

MTP 2 is located on top of MTP 1 and maintains reliable transmission via signaling link, status check and error check implementation. Total MTP 1-2 ensure reliable transmission over individual connections. The device would need an MTP 1-2 functional system for each link used. MTP 3 is located on top of MTP 2 and provides messages to the appropriate signaling link (actually to MTP 2 for this link). MTP 3 routes the messages to the application, using MTP 1-2 for access to the signaling system. MTP 3 also has a management function that controls the state of the signaling system and can make the right measurements to restore the service by the system. MTP levels 1-3 correspond to layers 1-3 of the basic OSIBRF connection reference model.

The SS7 242 interface also includes the ISUP functional arrangement of the user part of the digital network with service integration. It may contain ISUP clocks that produce a release message or retransmit the message if necessary. If B-ISUP signaling is used, the SS7 242 interface can also be equipped with the B-ISUP functional system. All these elements are known in the art. The SS7 242 interface can be constructed using commercially available SS7 software interface tools. An example of such tools is the SS7 interface software from Trillium, Inc. or Dale, Gesek, Mc Williams, and Sheridan, Inc.

The SS7 242 interface routes IAM messages from link 261 to the link processor 246. The SS7 242 interface also receives IAM from the link processor 246 and sends them via link 261. The SS7 242 interface will receive further messages related to SS7 calling from link 261. The SS7 242 interface will changed the routing labels of these subsequent messages and retransmitted them via link 261. Examples of these subsequent messages include full ACM address messages, ANM response messages, REL release messages, and full RLC release messages.

The routing label includes the DPC destination code, the OPC origin code, the CIC identification code, and the SLS signaling link selection code. The OPC and DPC codes identify the origin and intended purpose of the signaling message. For example, a message sent from point A to point B would have an OPC code for A and a DPC code for B. A return message would reverse both and would have an OPC code for B and a DPC code for A. The CIC code identifies the initiation circuit used for the call. The SLS code is used to enable load sharing between signaling links.

The following discussion refers to Fig. 1 and the related embodiment. When messages related to subsequent calls are received via the SS7 interface of the signaling processor 140, the OPC, DPC and / or CIC codes need not be changed. A message from the initial user 100 to the selected switch 130 would have the DPC and CIC codes changed to reflect the new DPC and CIC codes selected for connection by the signaling processor 140. This is because switch 130 waits for its own DPC and switch 130 also needs to know the actual DS0 used by the multiplexer 114 in connection. The message to the initial user 100 from node 130 would have changed the OPC code to reflect the DPC code in the original I AM from the user 100. This is because the user 100 expects response messages for the call from the point where the original LAM was sent. This point code is the DPC code of the original IAM. The CIC code is also changed to reflect the CIC code in the original IAM from user 100. This is because user 100 expects DS0 in the message to be DS0 used in connection 150. Messages between end user 102 and selected switch 130 would need changed CICs for reflect the actual DS0 used by the recipient of the message. The CIC code in messages from user 102 to switch 130 would reflect DS0 on connection 156. The CIC code on messages from switch 130 to user 102 would reflect DS0 on connection 151.

Returning to Fig. 2, connection processor 246 is adapted to process input LAMs and dial connections. For network calls, the connection processor 246 selects the narrowband switch to handle the connection and also selects connections to the narrowband switch. These connections are usually VPI / VCI combinations. If the connection is extended beyond the selected narrowband switch, the connection processor 246 identifies the required call recipient in the IAM from the narrowband switch. The connection processor 246 also selects connections to this recipient. These connections are usually VPI / VCI - DS0 combinations.

As discussed above, the signaling processor may be transparent to users. As a result, users will send signaling to the narrowband switch selected by the user. The recipient of this SS7 signaling message is identified by the DPC destination code. Thus, on calls entering the network, DPC indicates the narrowband switch selected by the user. The 246 connection processor typically uses this DPC to select a narrowband switch. It may be the same narrowband switch selected by the user or another narrowband switch. The connection processor 246 may then control the current usage of the selected narrowband switch. This may include reachable link access to the switch and / or the switch processing load. If access to the switch is overloaded or the switch CPU is heavily loaded, the substitute switch may be selected. In addition, special network operations may require a replacement switch - for example, if the switch is inactive during maintenance or testing.

After selecting the switch, the connections to the switch are selected. DS0 on the internal connection is identified by the CIC system identification code in the IAM. VPI / VCI is selected, which was previously provided through a cross connection from the multiplexer connected to the input DS0 to the multiplexer serving the selected switch. DS0 is selected from the last multiplexer to the selected switch. Based on the selections, LAM information is provided to the SS7 242 interface and control message information is provided to the multiplexer 244 interface.

As discussed above, after the narrowband switch has serviced the connection, it forwards the LAM to the recipient. The 246 connection processor will receive this IAM and use DPC to identify the recipient and select the correct connections with that recipient. The CIC code in the IAM identifies DS0 from the selected switch to the multiplexer. VPI / VCI from this multiplexer to destination multiplexer and DS0 from destination multiplexer to destination are selected. The selections are then made by the multiplexers in response to control messages from the signaling processor 240. The connection processor 246 also tracks the use and status of connections and connection groups for connections within the control range. It also receives network management information. .

In some embodiments, the connection processor 246 uses at least part of the dialed number to select a narrowband switch. For example, narrowband switch "A" can be assigned to area code "X". For connections to the area code 'X', switch A is selected. If switch "A" is not reachable, a substitute switch "B" can be used. This can also be done using the NPANxXx area code and exchange. In some embodiments, the number selected may correspond to a special service offered by the selected group of switches. For example, the number "1800-ΝΧΧ-ΧΧΧΧ" may correspond to the calling card service offered from only two switching nodes. The numbers "888" and "900" are also used in this way. Connection processor 246 can select one of these switches based on the number being dialed. In some embodiments, the calling subscriber number, usually referred to as ANI, can be used in a similar manner to select a switch for providing services to the calling subscriber. In some embodiments, the call may be directed to the switch based on the operator identified in the signaling. This information is found in the operator identification parameter in the IAM.

187 643

The multiplexer interface 244 receives information from the connection processor 246 indicating the connections to be made or disconnected. The multiplexer 244 interface receives this information and provides the appropriate control messages to the appropriate multiplexers. The multiplexer 244 interface may also receive acknowledgments from the multiplexers. As a result, the signaling processor 240 may provide ATM header information to the multiplexers for use in configuring ATM cell headers so that the cells are directed to the required recipient.

ATM multiplexers

Figure 3 shows one embodiment of a multiplexer that is specific to this invention, but other multiplexers that meet the requirements of the invention may also be used. Shown are: control interface 300, interface OC-3 305. Interface DS3 310. interface DSI 315, interface DS0 320, adaptive layer ATM AAL 330 and interface OC-3 735, control interface 300 exchanges control messages with the signaling processor. Typically, these messages contain DS0 - VPI / VCI interoperability assignments to be made through the AAL 330 adaptation layer. As such, this information is provided to the AAL 300 adaptation layer.

The OC-3 305 interface receives the OC-3 format and performs processing to DS3. The DS3 310 interface receives the DS3 format and converts it to DSI. The DS3 310 interface can receive DS3s from the OC-3 305 interface or from an external connection. The DSI 315 interface receives the DSI format and processes it to DS0. DSI 315 can receive DSI from the DS3 310 interface or from an external connection. The DS0 320 interface receives the DS0 format and provides an interface for the AAL 330 adaptation layer. The OC-3 335 interface is adapted to receive ATM cells from the AAL 330 adaptation layer and send them to a cross-connection.

The AAL 330 adaptation layer contains both a convergence sublayer as well as a SAR division and re-accumulation layer. The AAL 330 adaptation layer is adapted to receive user information in DS0 format from the DS0 320 interface and to process information to ATM cells. AAL adaptation layers are known in the art and information about AAL is provided by document 1.363 International Telecommunications Union (ITU). The AAL adaptation layer for voice is also described in patent application series 08/395 745, filed February 28, 1995, entitled "Cell Processing for Voice Transmission" and introduced herein by reference to this application. The AAL adaptation layer 330 receives the VPI virtual path identifier and the VCI virtual channel identifier for each call from the control interface 300. The AAL 330 adaptation layer also receives the DS0 identity for each cell or DS0 for the Nx64 call. The AAL adaptation layer 330 then processes user information between the identified DS0 and the identified virtual ATM connection. Confirmation that assignments have been made can be sent back to the signaling processor if needed. Calls at a data rate that is a multiple of 64 kbit / s are known as Nx64 calls. If desired, the AAL 330 adaptation layer may be able to receive control messages via the control interface 300 for Nx64 calls.

As discussed above, the multiplexer also supports calls in the opposite direction - from the OC-3 335 interface to the DS0 320 interface. This traffic would be processed to ATM by another multiplexer and directed to OC-3 335 through a cross connection with the selected VPI / VCI. The control interface 300 will provide the AAL 330 adaptation layer with the assignment of the selected VPI / VCI for the selected external DS0. The multiplexer will process ATM cells with the selected VPI / VCI in the cell headers to the DS0 format and deliver to the selected external DS0 connection. The VPI / VCI processing technique is disclosed in U.S. Patent Application Serial No. 08/653 852, filed May 28, 1996, entitled "Telecommunications System with Call Service System" and incorporated herein by reference.

DS0 connections are bi-directional and ATM connections are usually unidirectional. As a result, two virtual connections in opposite directions will usually be required

187 643 for each DS0. As discussed, this can be achieved by providing a cross connection with the VPI / VCI assembly in the opposite direction to the original VPI / VCI assembly. On each call, the multiplexers would be configured to automatically call a specific VPI / VCI assembly to provide a two-way virtual connection to match the two-way DS0 to the cell.

Understanding the preferred embodiment, those skilled in the art understand that the present invention allows a combination of high speed broadband transmission with systems configured for narrowband processing and control. By implementing the connection support function on narrowband switches, the broadband transmission capability is transparent to users and other existing network elements configured to interact with narrowband switches. In addition, broadband transmission is done economically and efficiently without the need for broadband switching nodes.

Those skilled in the art will recognize that variations of the specific embodiments disclosed above are contemplated by the invention. The invention should not be limited to the above embodiments, but should be defined by the following claims.

187 643

240

<img file="PL187643B1_D0001.tif" />

FIG. 2

187 643

300

305 310

INTERFACE

CONTROL

0C3

DS3

DS1

DSO

315 320

ATM (AAL) ADAPTIVE LAYER

330

0C3

V

335

FIG. 3

187 643

<img file="PL187643B1_D0002.tif" />

FIG. 1

UP Department of Publications. Circulation of 50 copies

Price PLN 4.00