System and apparatus for and method of effecting telecommunication signalling using an improved signalling station

Telecommunications signaling is the transmission of information used by telecommunications networks within and between networks. The signaling information is used to control the telecommunications networks such that the networks may convey other, non-signaling information to the network users. Examples of signaling operations are connection organizing, load control, and network management. A known standard for telecommunications signaling is Signal System 7 (SS7).

Signal Relay Stations (STPs) establish signaling routes within the SS7 network and manage the various signaling links that make up the SS7 network. The routing of the signals is performed by processing the routing included in the message of the SS7 network by a messaging device (MTP) function included in the signaling station. The MTP device has three functional levels. Levels 1 and 2 perform forwarding

183 244 SS7 network messages from one station to another over a single signaling link. Level 3 accomplishes the forwarding of messages in the SS7 network over and above the requirements for transmission over a single link. In other words, levels 1 and 2 are related to forwarding on individual links, while level 3 is related to forwarding on the entire SS7 network.

The STP performs the task of routing messages at level 3 by using station codes that identify the various signaling stations on the network. The STP level 3 identifies the destination station code in the SS7 message and selects the appropriate signaling link over which the message should be transmitted. For example, if switch A transmits signals to switch B via an STP, the message comprises the destination station code for the signaling station at switch B (and the transmitting station code at switch A). The STP station receives this signal from the signal link, reads the code of the destination station, and routes the message over the appropriate link to switch B.

The STP station may also control the signaling network using the management messages generated at level 3. In the above example, if there are signaling links between exchange A and STP, then the STP station may send instructions to exchange A advising to avoid particular links that are overloaded or broken. .

Telecommunications networks usually face the problem of changing the route of the message stream sent by users between exchanges. The message stream may require rerouting from one switchboard to another switchboard, from one switchboard to many switchboards, from multiple switchboards to one switchboard, or from one group of exchanges to another group of exchanges. When a message stream reaching the network is routed to a particular switchboard, we say the stream is assigned to the switchboard. The stream assigned to a given control panel may need to be assigned to other control panels.

The rerouting of the user message stream includes rerouting the connections between switchboards. Connections between panels can be added and removed to create a new network diagram. As a result of the relationship between the signaling and the network diagram, any change to the diagram must be reflected in the signaling system. This is usually done by reprogramming the control panels so that they transmit signals to each other according to the new scheme. This is a complicated and time-consuming task. The control panels contain numerous data files that must be reprogrammed in accordance with the new scheme of communication routes.

One of the known systems transfers the line from the old switchboard to the new one. The system processes the station codes in the signaling messages to the old control panel according to the changes in the line assignment from the old control panel to the new control panel. The processing is located between the exchange and the STP, so that it only handles signaling on the signaling link connected to the old exchange. A conversion table is used to process station codes. Since the individual lines are connected to either the new switch or the old switch depending on the assignment, the table can be constructed so that it identifies the particular line used to establish a connection and processes the station codes based on the assignments of the line, switch and station code.

This known solution is suitable in the limited scope in which individual lines are transferred from the old switch to the new switch, but it does not solve the problem of changing the network scheme to a greater extent. The existing solution provides support for two control panels that jointly support single transmissions and have a common signaling direction. In other words, the solution is limited to the situation where signaling which has already been directed to the old exchange is split between the old exchange and the new exchange when transferring the transmission between two exchanges.

As a result of this limitation, several problems were not solved by the known solution. Since it is based on identifying individual transmission lines to process the station code, the station codes cannot be processed in signals that cannot be assigned to a given line. It does not solve the problem of handling management messages that are generated to control the signaling system. Also, relying on the identification of individual lines does not adequately solve the problems with situations where the entire control panel load is transferred between control panels or when

183 244 the load of many control panels is directed to one control panel. Since all lines between control panels are changed, it is not necessary to distinguish between individual lines.

Moreover, the known solution does not identify the origin of the signaling message for selecting the signaling destination. So far, the messages that come from the new exchange are reviewed so that these signals can be processed to match the signals produced by the old exchanges. This is done to avoid confusion at the destination station, but does not affect the actual choice of destination. In the known solution, the destination is not selected based on the origin of the message, but only uses the line identification to select the destination. It is determined based on either a dialed number or a Circuit Identification Code (CIC).

It should also be noted that the legacy system is designed only to process the signaling that was placed on the signal link connected to the old switchboard. This means that the STP station already has isolated messages that are directed to the old exchange. Thus, the system does not receive signaling directed to another switch and it is not able to process signaling that was not routed to the old switch. In this way, the STP will only process the station codes after the STP has completed the route analysis and has directed the signaling to the old exchange. Thus, the STPs of the known solution cannot be used to process incoming signals, the path of which has yet to be determined and it is not known to which center they will be directed.

Another known solution provides signal transitions between two signal systems, for example transitions for signal systems used in Europe and the United States. The signal doorway processes station codes based on the network identification and destination station codes. The transition does not process station codes based on origin information such as signal link or the code of the transmitting station. The transition also processes station codes after the destination station code has been used to route the transmission of the message. Also, since the transition has to transform the signaling of the various signaling circuits, it has more functions and a higher price than the station code converter which does not have the transition function.

The essence of the method of processing signaling messages in a signaling station according to the invention, in which the signaling messages contain station codes, and a signaling data link function, a signaling link function and a signaling network function are used in the signaling station, is that during the processing of the station code, between data link function and signaling network function, converting at least some station codes in the signaling messages to other station codes before routing the signaling messages as a function of the signaling network.

Preferably, when processing the station code, the system identification codes are processed in the signaling messages.

Preferably, during station code processing, target station codes corresponding to the station codes received in the signaling messages are selected.

Preferably, during station code processing, target station codes are selected corresponding to the link set used to receive the signaling messages.

Preferably, the signaling messages include messages generated by the signaling network function.

Being. a method for processing signaling messages in a telecommunications system including a signal transfer station connected to a signaling processor, wherein according to the invention, the signaling station uses the functions of a portion of the transmitted message for signaling messages containing target station codes, the signaling processor being external to the telecommunications exchanges , it is, that the signaling station converts at least some of the target station codes in the signaling messages into a different target station code for the signaling processor and processes the signaling messages with this other target station code in the signaling processor.

Preferably, additional signaling messages containing the station origin code are transmitted to the signaling processor in the signaling processor and processed

183 244 in the signaling station, station origin code in additional signaling messages in other station origin codes.

An advantage of the solution according to the invention is that when the telecommunications network scheme is changed, the exchanges do not have to be reprogrammed in order to transmit the signaling according to the new scheme.

The subject of the invention will be described in the exemplary embodiments with reference to the drawing, in which Fig. 1 shows a block diagram of a signaling system, Fig. 2 a block diagram of a telecommunications network including a signaling system, Fig. 3 - a schematic diagram of an SS7 device, Fig. 4 - a schematic diagram of a device 5 is a schematic diagram of the STP function in the SS7 device, fig. 6 is a schematic diagram of the STP function according to another embodiment, fig. 7 - a block diagram of a telecommunications network with an STP; and Fig. 8 a block diagram of another telecommunications network with an STP.

SS7 signaling systems include basic components such as signaling stations, signal relay stations (STPs), and signaling links. The signaling stations process the signaling information to perform network operations. Signal links transmit signaling information between the various signaling stations. Figure 1 illustrates this fundamental relationship by showing a basic signaling system consisting of signaling stations 10, 11, 12, 13, 14, 15 and signaling links 21, 22, 23, 24, 25, 26, 27, 28. Links 2122,23,24,25,26,27,28 carry signaling used to control the network and actual lines that carry the stream of telecommunications messages are not shown.

A common example of a signal link is a 56 kbit / s data link included on a T1 line. However, these links can take various forms such as analog links, satellite links and 1.5 Mbit / s data rate links. Typically, links are grouped into multiple sets of links known as link sets.

The signaling stations process the signaling information transmitted over the signaling links. Often the signaling station is located inside the telecommunications switchboard. As is known, switchboards typically include a central processing unit (CPU), a signaling station, and a switchboard. The signaling station is connected to the CPU of the central and provides data so that the CPU can control the switchboard. The control panels communicate with one another by means of their signaling stations on signal lines. In this way, the distribution boards of the various control panels can be coordinated by the CPU of the control panel to establish a multi-control connection.

Signaling stations may also be located at service control stations (SCPs). SCP stations contain databases that give answers depending on the signals received from the switchboards. Usually, SCP stations receive a request from the central office: what route should be established for a given connection. The SCP station processes the signal and responds to the central office with a signal that provides information about the route. In addition to transmitting signals, an STP station may function as a signaling station. A plurality of signal links from a plurality of signaling stations are connected to the STP stations. The main function of STPs is routing, i.e., directing the incoming signals to the respective outgoing signaling links. Typically, signaling stations at switchboards and SCP stations are coupled to the STP and transmit signals to the STPs for routing to a suitable destination 'signaling station at another switchboard or SCP station. The STPs also perform management functions for the SS7 network.

It should be noted that in the solution according to the invention, other types of signaling stations may also be used, for example the above-mentioned signal processors may act as signaling stations. Additionally, other signaling systems such as C7 signaling may also be used.

Figure 2 shows the basic diagram of Figure 1 in a slightly different way. Fig. 2 shows switchboards 30,31, STPs 40,41, signal processor 45 and SCP 50, each device including a signaling station that is coupled to signaling stations in other network elements. As already mentioned, the signaling stations in the switchboards are usually connected to the CPUs of the switchboard that control the switchboard.

183 244

The SS7 signal itself is a point or a message containing bits of information. The device that processes SS7 signaling messages is generally divided into two parts: a messaging device (MTP) and a user device. The function of the MTP device is to transmit the SS7 message within the signaling system. User equipment functions are service user equipment (ISUP), telephone user equipment (TUP), transaction capabilities implementing device (TCAP), and signaling call control device (SCCP). These functions "use" the MTP device to transmit signaling messages over the signaling links of the SS7 network so that the user equipment can process information received by the exchanges, such as dialed numbers, processed numbers, and circuit status.

Since the STP is used for routing and managing the SS7 network, they do not need user equipment functions that relate to paging and connection information throughout the telecommunications network. The STP stations are responsible for establishing the routes of SS7 messages within the signaling networks to the appropriate signaling stations in the exchanges and SCP stations. The STP station uses the processing of the MTP device to perform this function. In addition, the STP may use signaling call control device (SCCP) logic for routing. SCCP devices allow routing of signaling messages based on logical connections. For example, a signaling message requesting the conversion of the dialed number can be sent to the STP itself. The SCCP devices will provide the STP with the station code for the corresponding database which can perform the conversion.

The operation of the MTP device has three levels: signaling data link (level 1), signaling link (level 2), and signaling network (level 3). Level 1 represents a bidirectional signal path with two data channels operating in opposite directions. Level 1 defines the physical and electrical characteristics of the signaling link. Typically this involves 56 kbit / s data link operation, however other forms of link may also be used. Level 2 operates over level 1 to deliver the signaling from station to station over a single data link. This includes tag supplementation to signaling messages, padding bits, error detection with check bits, error correction by retransmission and sequence information, signal link failure detection, and signal link repair. For example, in Fig. 1 and 2, the first two levels can be used to transmit on signal link 20 at 56 kbit / s from signaling station 10 at switchboard 30 to signaling station 11 at STP 40. The first two levels also ensure that the proper operation of the signal link is controlled. 20. Level 3 defines the forwarding functions that are independent of the operation of the individual signaling links, for example, from central office 30 to SCP stations 50 in Figure 2.

SS7 devices are shown in Figure 3 with MTP device 61 and user equipment 62. Separation of the MTP device and user equipment is shown. The MTP device 61 handles the transmission of signaling messages within the signaling network and the user equipment 62 controls the network that transmits the telecommunications stream. An example of a user device is a signal processor. The signaling data link 71 (level 1), which supports the physical-electrical transmission on the individual links, is connected to the signaling link 72 (level 2), which controls and controls the operation of the links. A signaling network 73 or level 3 is shown between the user equipment 62 (level 4) and the level 2. Level 3 provides the transition between the user equipment 62 and the transmission over the link. Level 3 also manages the SS7 network above the link level.

Figure 4 shows the above devices, in particular the level 3 device, in more detail. The functions of signaling data link 100 (level 1) and signaling link 200 (level 2), signaling network 300 (level 3), and user equipment 400 (level 4) have been discussed above. The signaling network 300 also includes a signaling message handler 310 that ensures that messages from user equipment 400 are delivered to the correct destination, primarily according to the route designation.

183 244 contained in the communication. Handling of the signaling message 310 includes identification 312, routing 314, and splitting 316.

Before discussing these elements, a brief description of the route markings will be given. The route identifier is included in each signaling message and is used by the respective user equipment to identify the destination of the message and is used by level 3 to process and route the message. The routing marker is usually placed at the beginning of the signaling information field. The route designator includes both the destination station code (DPC) and the transmitting station code (OPC). These codes identify the signaling stations in the network, and in particular, the transmitting and destination signaling stations for a given message. For example, a message sent from signaling station A to signaling station B will have the OPC A code and the DPC B code. The return message will have the opposite designations: OPC B code and DPC A code. The routing tag also includes a signal link check box (SLS) that is used to evenly distribute loads between the links.

Standard International Signaling has a 14-bit DCP code, a 14-bit OPC code, and a 4-bit SLS field. For example, standard signaling in the United States has a 24-bit DPC code, a 24-bit OPC code, and a 5- or 8-bit SLS field. The 24 bits of the US station code are divided into three 8-bit fields that identify, the signaling station, the network, and the group to which the station code belongs. The 8 bit group member code 00000000 is reserved for STPs. It should be noted that other signaling conventions may also be used in the present invention.

Referring to FIG. 4, the identification function 312 analyzes the DPC of the message to determine whether a given signaling station, performing the identification function, is the destination of the message. If it is not the destination, the message is routed to routing 314 for transmission over the signaling network. If it is the destination, the message is routed to a split function 316 for internal processing.

The splitting function 316 analyzes the service pointer in the message to route the message to an appropriate user at user equipment 400 or to a suitable function in managing the signaling network 320.

Routing 314 receives messages from distribution 312, user equipments 400, and signaling network management. 320. Routing 314 determines on which signal link messages should be sent and transmits the messages to level 2 for transmission. Typically, the DPC is used to select a combination link set, and the SLS field is used to select a link within the combination link set over which the message is to be sent. The DPC controls the actual destination of the message, but many other factors can affect the route selection, such as link congestion or broken links. The signaling network management function 320 provides this type of information to the routing function 314.

The management of the signaling network 320 includes the following functions: managing the signaling link 322, managing the signal path 324, and managing the signal stream 326. The primary function of these elements is to control the signaling network in the event of faults and overloads.

Signal link management 322 controls the status of individual links. It may use the following procedures to control links: link activation, link deactivation, link restoration, link set activation, and automatic allocation.

Signal route management 324 broadcasts link state information. The information may indicate broken or congested links and includes: Forbidden, Allowed, Restricted, Controlled Transfer, Signal Route Set congestion test, and Transport Route Set test.

Signal stream management 326 is used to change signaling routes to adapt to the state of the transmission system, e.g., to account for failures or congestion. Signaling may be moved or partially moved (forbidden) from one link to another. These are the procedures: transfer, withdrawal, forced

183 244 rerouting, controlled rerouting, MTP device restart, non-management flow control.

Typically, an STP station includes the above-described functions of an MTP device, where the functions of the STP station may be changed to provide advantageous functions to the telecommunications network.

Figure 5 shows the functions of an STP in a schematic diagram. Generally shown are: signaling data link 100 (level 1), signaling link 200 (level 2), signaling network 300 (level 3), and user equipment 400 (level 4). In addition, the functions identification 312, routing 314, splitting 316, managing the signaling network 320 are shown as functions of the signaling network 300. These functions interact with each other as discussed above with the following modifications.

Station code processing 500, shown between level 2 and level 3, is added. Station code processing 500 receives messages from level 2 and provides messages for identification 312. Station code processing 500 processes data in signaling messages using internal tables. Typically these tables are logically located in the MTP device software executed by the STP. The tables are used to systematically change the specific DPC, OPC, and CIC codes in the signaling messages directed for identification 312.

The appropriate table may be selected based on the link sets or signaling groups in which the messages appear. Link sets and groups represent the origin of the messages. Tables can also be selected or analyzed based on the OPC code which also represents the origin of the messages. The tables can then use the OPC, DPC, and / or ClC codes of the message to select new data for processing, including the new OPC, DPC, and / or CIC code. Since routing 314 selects the outbound link based on the DPC, processing the station code 500 may alter the actual destination of the signaling message. The tables are structured so that the desired changes can be made.

Alternatively, only the DPC code may be used for all processing. The table takes the DPC code to convert the DpC code. In addition, at a location in the STP where processing is still link set dependent (before level 3), processing in the MTP device for the link set will flag messages received from the specific link sets. Incoming messages from given link sets will be allowed to access the table on the next processing when a tag is detected and untagged messages will not be able to access the table. The table can convert OPC, DPC and / or CIC code combinations into the appropriate OPC, DPC and / or CIC code combinations.

Referring again to Fig. 4, it can be shown how the identification 312 can be changed in accordance with the invention. As said, identification 312 determines whether the messages are intended for the STP itself, the user equipment, or another signaling station. A conversion table that is based on the link set, OPC, DPC and / or CIC codes may be functionally located at this station. The table may process all signaling messages, messages not routed to the DPCs of a given STP, or messages tagged from previous processing. The solution according to the invention thus applies to the code processing function of the station located in the identification 312. The processed messages are usually forwarded to a split 316 in this case.

In one embodiment, an STP that has a particular analysis input function is used. The function analyzes incoming messages using a set of criteria specified for each link set delivering the messages. Criteria ensure that the messages are valid for a given link set. Currently, the function only analyzes messages and does not process them or modify station codes. In this embodiment, the station code processing 500 is located in the STP between the levels and 3 in the station having the analysis input function. Alternatively, only a tagging function can be placed in the input analysis function and the conversion table can transform the tagged messages during subsequent processing.

183 244

By placing the conversion tables at an STP that is specific to the incoming link set, the station code processing can be provided for signaling stations transmitting signals over the given link set. In other words, the signal processing can be defined individually depending on the origin of the signals. This location also allows the level 3 functions to process the processed signal, instead of processing the signal first and then converting the station codes at the output. Similar benefits can be obtained by tagging messages on specific link sets and using the OPC code for origin determination during subsequent processing.

User equipment 400 (level 4) may include a signal processor that can process specific user equipment ISDN service signals (ISUP). In at least one embodiment, the identification 312 is configured to identify the specific ISUP messages required by the signaling processor. These criteria can be formulated as a table and the table used to identify the appropriate ISUP messages from the identification 312 for transmission to the function processor. Like the station code conversion tables, the signaling origin represented by the link set or the OPC code can be used to determine if an ISUP message should be sent to the appropriate user equipment. OPC, DPC, CIC and SLS box codes and various combinations of these elements can also be used for this purpose. In addition, the tagging function may be used during link set-based processing to trigger an ISUP message to be moved to user level 4 during subsequent processing.

Another embodiment is shown in figure 6, where the same elements are shown as in figure 5 with one supplement. In this embodiment, additional station code processing may be required for messages produced by managing the signaling network 320 or user equipment 400. In these embodiments, station code processing 350 is added and shown between management of the signaling network 320 and routing 314, as well as between user equipment 400 (level 4) and routing 314. Station code processing 350 works by using tables, as does station code processing. 500. In this way, station codes in management messages or from user equipment can be processed. Typically the changes result from changes to the schema in a manner similar to the processing of the station code 500.

As mentioned above, the management of the signaling network 320 includes three functions: signal link management, signal stream management, and signal path management. For example, if a signaling link fails, signaling link management will detect this and inform signal stream management, which will forward the signals to other signaling stations to route signaling on the other link. If this were to cause congestion on the alternative link, the signal path management would send signals to other signaling stations instructing them to limit the use of the congested link.

Typically, signal link management messages do not require station code processing. However, signaling flow management messages and signaling route management messages provide other signaling stations with signaling instructions for the distinguished links and signaling stations. Station codes are used to identify the distinguished links and signaling stations. These messages require changing the station identification codes to reflect the new network scheme. These changes are handled by tables as described above for the station codes used for routing. The management messages may be related to each signaling station receiving the messages by using the DPC in the route designation using the table. The table is structured to give each signaling station that receives the management message the station codes it accepts in a given station code processing scenario.

Another embodiment is shown in Figure 7, which shows a block diagram of a telecommunications network including an enhanced STP 600. STPs 605 and 610

183 244 are shown with exchanges 615, 620, 625, 630, 640, 645, 650, 655, 660, and 665. STPs 605 and 610 are standard STPs, and exchanges are also standard telecommunications exchanges.

In Fig. 7, signal links are represented by double lines and telecommunication links are represented by single lines. The exchanges and STPs are connected by signaling links 700, 705, 710, 720, 725, 730, 735, 740, 745 and 750 as shown in the drawing. These links carry signaling between exchanges and STPs, as discussed above. As can be seen in the figure, there are connections 760, 765, 770, 775 and 780 between the exchanges, which carry a stream of telecommunications messages for users of the telecommunications network.

In order to understand this embodiment, it should be emphasized that the network diagram is a modified diagram where the previous connections are not shown: the connection from switch 620 to switch 650 has been transferred to switch 640, connection from switch 625 to switch 655 has been transferred to switch 645, connection from switch 630 to switch 660 was transferred to switch 645, and connection from switch 635 to switch 665 was transferred to switch 645. The connection from switchboard 615 to switchboard 650 has not changed. The control panels have been reprogrammed to accept signaling in accordance with the new scheme. Additionally, STPs 605 and 610 have not been improved in accordance with the invention.

When switchboard 630 tries to connect to switchboard 660 according to the previous connection, it actually connects to switchboard 645. However, switchboard 630 will still route signals to switchboard 660 trying to establish a connection. Signaling will be directed to STP 600 and processed according to the invention. The DPC code in the signaling will be processed to represent the switch 645 instead of the switch 660. The signaling will then be routed to switch 645. When exchange 645 responds to exchange 630 confirming the connection has been established, STP 600 will convert the OPC code from exchange 645 to represent exchange 660. In this way, exchange 630 can send signals and make calls according to the new scheme without reprogramming.

When switchboard 620 tries to connect to switch 650 (according to the previous connection), it actually connects to switch 640 over connection 765. However, switchboard 620 will still try to send signals to switch 650. Signaling will be on link 705 through STP 605 and on link 710 to STP 600. The DPC code will be converted by STP 600 to represent switch 640 instead of switch 650. The signaling will then be routed to switch 640 over link 745. When switchboard 615 tries to connect to switchboard 650, according to the previous and current connection, it will send a signal to switchboard 650. The signal will be routed via link 700 through STP 605 and via link 710 to STP 600. W in this case no transformation is needed. Thus, sometimes STP 600 should process the DPC for exchange 650, and sometimes not. The present invention allows STP 600 to discern whether or not to perform the conversion.

STP 600 identifies the source of the signaling before performing the processing. This identification may be based on the OPC code. Thus, the processing for exchange 615 will be different from that for exchange 620. For exchange OPC code 615, the DPC code for exchange 650 will not be changed. For panel OPC code 620, panel DPC code 650 will be changed to panel DPC code 640.

Additional signaling messages sent in reverse direction may be converted in the STP in a similar manner. For example, messages from switch 645 to switch 630 and switch 640 to switch 620 will have their OPC code changed to represent switch 660 and switch 650 respectively. In the message from the 650 to the 615, the OPC code does not need to be changed.

Station codes may also be changed at STP 600 based on the signaling link from which the message originated. For example, the signaling from switch 650 to switch 615 does not require processing, but the signaling from switch 640 to switch 620 requires processing due to the new scheme. STP 600 is configured to process the OPC code for signaling messages arriving on signaling link 745 into an OPC code for switch 630. STP 600 does not translate the OPC for signaling messages arriving on signal link 740 (sy183 244). As can be seen, the processing may be based on many factors, such as signal link, OPC codes, DPC, CIC, and SLS fields, and various combinations of these factors, with which can also take into account other factors.

As stated above, signaling networks use management messages to control the signaling network. An example of such messages is the transmission load reduction message. If link 750 between STP 600 and switch 750 becomes congested, signal path management at STP 600 will generate and send transmit load limitation messages to reduce load on link 750. The link is congested in the signaling determined by the station code for the exchange 645, the message still requiring separate OPC and DPC codes in the route designation for its own routing. However, other exchanges in the network did not recognize the station code for the 645 because they had not been reprogrammed. For this reason, they do not recognize the congested link 1 and can continue to use it. STP 600 will convert the station codes in management messages that define the congested link into station codes that will be recognized and appropriately used by the signaling stations receiving the management messages.

Each signaling station may have an individual processing method to receive the traffic load limitation message. This is accomplished by using the DPC in the management message routing to identify the receiving signaling stations and obtain their appropriate transformations. For example, the site code assigned to the congested link may belong to switch 625 for a message sent to switch 625 and may belong to switch 660 for a message to switch 630. In this case, the DPC in the route identifier is used to select the appropriate code conversion method. station assigned to the congested link. In some cases, conversion may not be required for some management message destinations. For example, a message about transmission load limitation on link 740 that is sent to switch 615. Message origin recognition may be used to distinguish if a conversion is needed.

Figure 8 is a block diagram of another telecommunications network. Exchange 810 is connected to STP 830, and exchange 820 is connected to STP 840. Signal processor 850 is connected to STP 830, and signal processor 860 is connected to STP 830 and to STP 840. If exchange 820 sends a message to central office 810 via STP 840, the STP 840 may convert the DPC code to represent the station code of signal processor 860. As such, a message will be sent to signal processor 860. A message from signal processor 860 to switch 820 may have an OPC code converted by STP 840 to represent the OPC code of switch 810. Thus, switchboard 820 does not need to be reprogrammed to communicate. with the 860 signal processor.

Additionally, signal processor 850 may act as a user equipment at STP 830. If switch 810 is to transmit a signal to switch 820, STP 830 may send a signal to signal processor 850 instead of switch 820. After the message is converted, the signal processor may transmit a message to switch 820 and STP 830 may convert the OPC code to identify switch 810. Messages from switch 820 to switch 810 may be transmitted in a similar manner. In this way, signal processor 850 can transform signaling between exchanges in a manner that is transparent to the exchanges.