Signaling System #7, Fifth Edition (McGraw-Hill Computer Communications Series)

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In step , soft switch queries route server to receive a call route and to allocate circuits to connect the call. Route server is responsible for using the DDD number to select a least cost route through data network , and allocating a terminating circuit for this call. Additional information on how soft switch interacts with route server and terminating soft switch is described in the Specific Implementation Example Embodiments Section below, in the section entitled Route Server.

In step , route server returns a route that indicates the connections that soft switch must make to connect the call.

In step , soft switch communicates with soft switch to allocate ports in trunking gateway of gateway site , for termination of the call. Soft switch is located in a central soft switch site In step , soft switch queries port status of route server to identify available ports in trunking gateway In step , route server returns an available port to soft switch In steps and , soft switch communicates with trunking gateway to allocate a port for termination of the call to called party In step , soft switch communicates with soft switch to indicate terminating ports have been allocated.

In steps and , soft switch communicates with trunking gateway in order to notify trunking gateway to set up an RTP session i. The Specific Implementation Example Embodiments Section, in the next section, describes additional information about, for example, how soft switch performs initial digit analysis to identify the type of call, and how to process the call.

The next section also describes how soft switch interacts with other components of the voice network architecture in transmitting the call. Various embodiments related to structures, and operations between these structures described above are presented in this section and its subsections. These embodiments are described herein for purposes of illustration, and not limitation. The invention is not limited to these embodiments.

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Alternate embodiments including equivalents, extensions, variations, deviations, etc. The invention is intended and adapted to include such alternate embodiments. Specifically, this section provides a detailed description of the VOIP network architecture according to the present invention. A structural implementation of the VOIP network architecture is described at a low-level. Also, a functional implementation for this structure is described at a low-level.

A more detailed structural description of telecommunications network will now be described. Specifically, FIG. These soft switch sites include western soft switch site , central soft switch , and eastern soft switch Telecommunications network also includes a plurality of gateway sites that may be collocated or geographically diverse.

These gateway sites include gateway sites a, b, a and b. Data network can route both signaling and transport traffic between the regional soft switch sites and regional gateway sites. For example, data network can be used to route traffic between western soft switch site and gateway site a.

Signaling and transport traffic can also be segregated and sent over separate data networks. As those skilled in the art will recognize, data network can be used to establish a data or voice connection among any of the aforementioned gateway sites a, b, a and b under the control of any of the aforementioned soft switch sites , and Western soft switch site includes soft switch a, soft switch b, and soft switch c.

Soft switches a, b, c can be collocated or geographically diverse. Soft switches a, b, c provide the features of redundancy and high availability. Failover mechanisms are enabled via this architecture, since the soft switches can act as one big switch. Soft switches a, b, c can intercommunicate via the inter soft switch communication protocol, permitting access servers to reconnect from one soft switch to another.

This architecture enables centralization of SS7 interconnection to gain economies of scale from use of a lesser number than conventionally required of links to signaling network , to be shared by many access servers in gateway sites. ESs , also provide connectivity to routers Rs , Routers , respectively provide redundant connectivity between redundant ESs , and data network As noted, included in telecommunications network are central soft switch site and eastern soft switch site Central soft switch site and eastern soft switch site respectively include identical configurations to the configuration of western soft switch site Gateway sites b, a and b have similar configurations to gateway site a.

The details of gateway site a, b, a and b will be further described below with reference to FIG. Referring back to FIG. Call processing refers to the handling of voice and data calls. There are a number of important call processing functions handled by soft switch Soft switch processes signaling messages used for call setup and call tear down. These signaling messages can be processed by in-band or out-of-band signaling. For an example of out-of-band signaling, SS7 signaling messages can be transmitted between signaling network and soft switch Soft switch refers to soft switches a, b and c.

Another call processing function performed by soft switch is preliminary digit analysis. Preliminary digit analysis is performed to determine the type of call arriving at soft switch The customer trigger plan effectively identifies the service logic to be executed for a given customer. This trigger plan is similar to a decision tree pertaining to how a call is to be implemented. Subsequently, soft switch executes the customer trigger plan.

This includes the processing of special service calls requiring external call processing, i. Another important function soft switch is communicating with RS to provide network routing information for a customer call. For example, soft switch can query RS to retrieve the route having the least cost from an off-network calling party homed to gateway site to an off-network called party homed to gateway site over data network Upon finding the least cost route, soft switch allocates ports on TGs , As described in detail below, soft switch can also be used to identify the least cost route termination and allocate gateway ports over AGs , between an on-network calling party homed to gateway site and an on-network called party homed to gateway site This primary soft switch, e.

In addition, the access servers can be as respectively assigned to secondary switches, which control the access servers in the event that the primary soft switch is unavailable. For example, western soft switch site can be a soft switch site located in San Diego, CA. Central soft switch site can be a soft switch site located in Denver, CO.

Eastern soft switch site can be a soft switch site located in Boston, MA. It is permissible that additional network nodes are provided at any of soft switch sites , and For example, additional elements, including, e. Referring to the more detailed implementation of FIG. The soft switch interfaces of FIG. Soft switch interfaces with configuration server over interface Soft switch interfaces with route server over interface Soft switch interfaces with SCP over interface Soft switch interfaces with announcement servers , over interface Soft switch interfaces with TGs , over interface Soft switch interfaces with AGs , over interface In one embodiment, soft switch is an application software program running on a computer.

The structure of this exemplary soft switch is an object oriented programming model discussed below with reference to FIGs. Another interface to soft switch not shown is a man-machine interface or maintenance and monitoring interface MMI. MMI can be used as a direct controller for management and machine actions. It should be noted that this is not intended to be the main control interface, but is rather available to accommodate the need for on-site emergency maintenance activities. Yet another interface permits communication between soft switches , A soft switch-to-soft switch interface will be described further with reference to FIG.

A soft switch to-soft switch interface permits communication between the soft switches , that control the originating call-half and terminating call-half of call flow The soft switch to-soft switch interface allows soft switches , to set up, tear down and manage voice and data calls. The near-end signals the far-end by applying volts DC "VDC" to the "M" lead, which results in a ground being applied to the far end's "E" lead.

This special line interface is quite different from that which the PBX uses to interface to directly-attached phones. The basic reason for the difference between a normal extension interface and a long distance interface is that the respective signaling requirements differ. This is true even if the voice signal parameter, such as level and two-wire, four-wire remain the same. When dealing with tie lines or trunks, it is costly, inefficient, and too slow for a PBX to do what an extension telephone would do, i. At least five different versions exist. The sample configuration depicted in FIG.

In FIG. TGs , are connected to the switch circuit network SCN , i. The originating soft switch can receive a call over any of these trunks. The signaling information from these SS7, ISDN, and in-band trunks is processed by soft switch to establish the originating call-half. The signaling information processed by soft switch , can be used to determine the identity of terminating soft switch The identity of terminating soft switch is required to complete the call.

Originating soft switch can then communicate the necessary information to complete the call, via an inter-soft switch communication ISSC protocol. Terminating soft switch can be required to be able to establish the terminating call-half on any of the supported trunk types. The messages can contain a header followed by a number of tag-length-value attributes. The incoming signaling message for the call being placed, can be carried in a general data block of one of the attribute value pairs AVPs.

The other AVPs, can contain additional information necessary to establish a voice-over-IP connection between the originating and terminating ends of the call. SS7 GWs , can intercommunicate as represented by connection to balance their loads. Load-sharing results in a completely fault resilient hardware and software system with no single point of failure. Each SS7 GW , can have, for example, six two-port cards for a total of twelve links to signaling network In an example embodiment, SS7 GWs The core of OMNI resides logically below the service applications, providing a middleware layer upon which telecommunications applications can be efficiently deployed.

Since the operating system is not encapsulated, service applications have direct access to the entire operating environment. These core protocols are supplemented with a higher layer of protocols to meet the needs of a target application or service. OMNI supports multiple protocol stacks simultaneously, each potentially with the point code format and protocol support of one of the major SS7 variants. Figure 5A depicts SS7 gateway to soft switch distribution Soft switches receive signaling messages from signaling gateways. SS7 GWs , communicate with soft switches a, b, c, via redundant connections from the soft switches a, b, c to distributions , , of SS7 GWs , respectively.

Based upon an SS7 network design, a pair of SS7 gateways receive all signaling traffic for the trunking gateway TG circuits serviced by the soft switches at a single soft switch site. Specifically, a pair of SS7 GWs , receive all signaling traffic for circuits serviced by soft switch site Signals serviced by soft switch site enter telecommunications network from gateway sites , , In an example embodiment, 96 circuits are serviced by each gateway site , , Gateway site includes TGs a, b. Gateway site includes TGs , A circuit is identified by a circuit identification code CIC.

TG a includes line card access to a plurality of circuits including CICs of gateway site TG b provides line card access to CICs of gateway site TG provides line card access to CICs TG provides line card access to CICs of gateway site TG a provides line card access to CICs Thus, CICs , ,, and CICs , , are the trunking gateway circuits serviced by soft switch site In an example embodiment, soft switches are partitioned such that any single soft switch will only service a subset of circuits serviced at a given soft switch site.

In order to assure that all signaling messages for a particular call get to the correct one of soft switches a, b. It is much more efficient to run SS7 links to soft switches than to each individual access server compare to the conventional approach requiring an SS7 link to each SSP. Centralization of SS7 signaling traffic interconnection enables benefits from economies of scale, by requiring less SS7 interconnection links. An exemplary technique for distributing circuits across soft switches a, b, c is based upon the originating point code OPC , destination point code DPC , and CIC.

OPC represents the originating point code for a circuit group, i. Similarly, DPC represents the destination point code for a circuit group, i. Soft switch site has a point code of value , and an alternate point code of value Soft switch site can act as one big switch using a flat network design of the present invention. This flat network design simplifies routing of calls. To support distribution of circuits across soft switches a, b, c, SS7 GWs , can include a lookup table that allows each signaling message to be routed to the correct soft switch a, b, c.

This lookup table is built on SS7 GWs , based upon registration messages coming from soft switches a, b, c. In an example embodiment, each time a TG boots up, the TG finds a soft switch to service its circuits. For example, when TG a is powered up, TG a must find a soft switch a, b, c to service its circuits, i. CICs In an exemplary technique, TG a sends registration messages to soft switch a to register circuits CICs Upon receipt of these registration messages the soft switch a registers these circuits with SS7 GWs , , at soft switch site The circuit registration messages sent to the SS7 gateways are used to build the type of table shown in Table 6.

Equals the LEC point code. Primary DPC Primary destination point code for the circuit group. Equals the Soft Switch site point code. The format of a registration message is shown in Table 7. Table 7 includes the mapping of circuits to soft switches. Each message also contains information about the soft switch that will be servicing the signaling messages for the circuits being registered. The soft switch information includes an indication of whether this soft switch is identified as the primary servicing point for calls to these circuits, the secondary servicing point or the tertiary servicing point.

The gateway uses this indicator in failure conditions, when it cannot contact the Soft Switch that is currently servicing a set of circuits. Figure 5A illustrates, and Table 7 represents in tabular form, the associations between circuit trunk groups ofTGs a, b, , , , and soft switches a, b, c. SS7 GWs , distribute incoming SS7 signaling messages to the soft switch a, b, c listed as associated with the particular circuit in the circuit to soft switch mapping lookup table, i.

The IAM includes the following information:. The IAM message can then be routed by signaling network i. SS7 GWs , can perform a lookup to Table 7, to identify which of soft switches a, b, c is handling the particular circuit described in the IAM message. Western soft switch site includes three soft switches a, b, c redundantly connected to routers , and SS7 GWs , via ethernet switches , Similarly, central soft switch site includes soft switches a, b, c redundantly connected to routers , and SS7 GWs a, b via ethernet switches , Finally, eastern soft switch site includes soft switches a, b, c redundantly connected to routers , and SS7 GWs a, b via ethernet switches , Data network can carry data including control message information and call traffic information.

Out-of-band signaling, such as, e.

Electronic Resources

Specifically, signaling messages intended for soft switch sites , , , are routed via packet switched SS7 signaling network to STPs , which are part of the SS7 national signaling network STP services i. Table 19 defines SS7 signaling links. Some of the SS7 links used are as follows. STPs , are linked together by a C-link.

STP pairs a, a are linked together by one or more C-links STPs , , a, a, , , b, b, , and can be linked by one or more A-links to SS7 GWs , , a, b, a, and b. Thus, signaling messages from anywhere in signaling network may be routed by STPs , through STPs , , a, a, , , b, b, , , to SS7 GWs , , a, b, a, and b of soft switch sites , , and SS7 GWs , , a, b, a, and b thus route messages through packet switched STPs to signaling network SS7 GWs , , a, b, a, and b use a separate physical interface for all simple network management protocol SNMP messages and additional functions that may be defined.

Exemplary functions that may be defined include provisioning, updating, and passing special alarms, and performance parameters to the SS7 GW from the network operation center NOC of network management component Signal transfer points STPs , are the packet switches of signaling network STPs , receive and route incoming signaling messages toward the proper destination. STPs , also perform specialized routing functions.

STPs are customarily deployed in pairs. While elements of a pair are not generally collocated, they work redundantly to perform the same logical function. STPs have several interfaces. The interfaces can be described in terms of the links used. Table 19 shows links used in SS7 architectures. D-links connect mated STPs at different hierarchical levels to one another. The second interface comprises C-links. C-links connect mated STPs together. An example are C-links between STP a and a. C-links enable STPs a, a to be linked in such a manner that they need not be co-located.

The entire soft switch site is viewed as an SSP to a signaling network. A-links or E-links can be used to connect any of STPs , , a, a, , , b, b, and respectively to soft switch sites , , at SS7 GWs , , a, b, a and b. In an example embodiment, each of SS7 GWs , , a, b, a, b can have, for example, twelve 12 A-links distributed among STPs a, a, b, b and STPs , , , , , By using the plurality of A-links, the soft switch sites , , have a fully redundant, fully meshed, fault tolerant signaling architecture.

STPs a, a, b, b use a separate physical interface for all SNMP messages and additional functions that can be defined. Additional functions that can be defined include provisioning, updating, and passing special alarms and performance parameters to and from STPs a, a, b, b and network operation center NOC of network management component In another embodiment of the invention, as illustrated in FIG. Additional soft switches and SS7 GWs can be used, for example, for handling additional traffic and for testing of alternative vendor soft switches and SS7 GWs.

SS7 GWs , are connected to soft switches a, b, and c. Eastern soft switch site also includes soft switch , which is connected to SS7 GW which is in turn connected to STPs b, b. Alternative embodiment , by including additional soft switches and SS7 gateways, permits additional redundancy and enables testing of alternate devices for connection to signaling network via STPs a, a, b, b, and STPs , can be equipped with a plurality of links.

In an example embodiment, STPs , can support up to, for example, 84 links. For example, in a preferred embodiment, 14 links can be used initially, and additional links can be added in the future. In a preferred embodiment, several additional features can be added to STPs , In a preferred embodiment, STPs , can have global title translation capability.

Global title translation uses global title information. Global title information is information unrelated to signaling network address, which can be used to determine the appropriate destination of a message. Global title translation can support translations from, for example, one to twenty-one digits. For example, translations can be assigned to translation types from 0 to In a preferred embodiment, STPs , can support up to, for example, 1, global title translation requests per second, per application service module ASM.

In a preferred embodiment, STPs , include a gateway screening software feature. EAGLE STP can support user definitions of up to 64 screen sets In this embodiment, each screen set can accommodate up to 2, condition statements or rules with the gateway screening software. Gateway screening can be performed on all in-bound messages from another network. Gateway screening can also be performed on all outgoing network management messages. Since gateway screening can occur on the link interface modules LIMs and the application service modules ASMs , the deployment of the gateway screening feature does not impact link throughput capacity, and can contribute to less than 5 milliseconds increase to cross-STP delays.

An advantage of the integration of LNP functionality is that it eliminates the need for costly external LNP databases, and associated transmission equipment. In one embodiment, LNP portability can support, complete scalabilty in configurations ranging from , translation entries and up to more than several million translation entries for very large metropolitan serving areas MSAs. Soft switch processing uses IPDC for gateway communication and uses off-switch call processing to access SCPs , , , SCP is connected to custom IP SCPs and other devices, such as route servers, can use this common interface.

Off-switch call processing abstraction layer is intended to be a flexible interface, similar to TCAP in function, that allows interaction between any type of SCP or other call processing logic and soft switch The abstraction layer is so designed that interfaces to a set of call processors supporting a specific function e. The field values for messages supplied by off-switch call processing abstraction layer are identified in this section i.

These services are recognized by those skilled in the art. Additional services and capabilities can include intelligent peripherals. Intelligent peripherals can include calling card, debit card, voicemail, unified messaging, conference calling, and operator services. These peripherals are recognized by those skilled in the art. The communication can be performed by the H. Soft switch gains signaling information from signaling network via STP , through SS7 gateway Gateway site , in intelligent network architecture , is connected to multiple off-network service providers.

Off network service providers include local exchange carrier LEC , inter-exchange IXC carrier and operator services service bureau Thus calls coming in from LEC or from IXC into gateway site , if identified as an operator call, may be routed to off-network operator services Soft switch does not dictate any particular SCP interface, but it is assumed that this interface will support the following types of interactions: 1 route request; 2 route response; 3 call gapping; and 4 connect to resource.

A route request is a message sent from soft switch to an external SCP The route request is sent to request a translation service from SCP , for example, to translate disclosed digits to a destination number. A route response is a message sent from SCP to soft switch in response to a route request. The route response includes a sequence of prioritized destinations for the call.

SCPs that perform routing can return a list of prioritized destinations. These destinations can be, for example, any combination of destination numbers or circuit groups. If SCP returns a destinations number, soft switch can attempt to route to that destination number using the least cost routing logic included in route server If SCP returns a circuit group, the soft switch can use route server to select an available circuit in that group.

Soft switch can try to terminate to the specified destinations in the prioritized order that the destinations are returned from SCP The interface that can be used by soft switch , in order to interact with SCPs , , , and , is called the off-switch call processing OSCP interface. This interface is also used for route server and any other call processing engines. Tables 8, 9, 10, and 11 identify the fields in the OSCP route request and route response messages, which are necessary for and account code processing service calls.

A route response can also include an indication to initiate a call gapping for a congested call. Call gapping refers to a message sent from an SCP to a soft switch to control the number and frequency of requests sent to that SCP. The call gapping response can indicate a length of time for which gapping should be active, as well as a gap interval, at which the soft switch should space requests going to the SCP.

For example, if SCP supports and project account code queries, it may gap on , but not on project account codes. Alternatively, SCP can gap on project codes but not on , or can gap on both or neither. A connect-to resource is a response that is sent from the SCP to the soft switch in response to a route request for requests that require a call termination announcement to be played.

For example, calling card interactive voice response IVR services can be provided off-switch, similarly to operator services Project account codes are discussed further below. Basic toll-free services are also discussed further below. For example, FIG. In addition, network IVR is depicted. Specifically, IP-Client is connected to data network via customer network Customer network is connected to data network and communicates via an H. SCP gateway can be used to communicate with customer premises toll-free facilities.

Customer premises toll-free facilities can communicate with computer telephony integration CTI server The H. By complying with the H. Therefore, the H. Version 2 was approved in January The standard is broad in scope and includes both stand-alone devices and embedded personal computer technology as well as point-to-point and multipoint conferences. Known as H.

Terminals , , are the client endpoints on the LAN that provide real-time, two-way communications. All terminals must support voice communications; video and data are optional. It is the dominant standard of the next generation of Internet phones, audio conferencing terminals, and video conferencing technologies.

All H. Three other components are required: Q. Optional components in an H. Gateway is an optional element in an H. Gateways provide many services, the most common being a translation function between H. This function includes translation between transmission formats i. In addition, gateway also translates between audio and video codecs and performs call setup and clearing on both the LAN side and the switched-circuit network side. In general, the purpose of gateway is to reflect the characteristics of a LAN endpoint to an SCN endpoint and vice versa.

The primary applications of gateways are likely to be:. Gateways are not required if connections to other networks are not needed, since endpoints may directly communicate with other endpoints on the same LAN. Terminals communicate with gateways using the H. With the appropriate transcoders, H. Many gateway functions are left to the designer. For example, the actual number of H. By incorporating gateway technology into the H. Gatekeeper is the most important component of an H. It acts as the central point for all calls within its zone and provides call control services to registered endpoints.

In many ways, an H. Gatekeepers perform two important call control functions. The second function is bandwidth management, which is also designated within RAS. For instance, if a network manager has specified a threshold for the number of simultaneous conferences on the LAN, the Gatekeeper can refuse to make any more connections once the threshold is reached. The effect is to limit the total conferencing bandwidth to some fraction of the total available; the remaining capacity is left for e-mail, file transfers, and other LAN protocols.

This collection of elements is known as an H. An optional, but valuable feature of a gatekeeper is its ability to route H. By routing a call through a gatekeeper, it can be controlled more effectively.


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Service providers need this ability in order to bill for calls placed through their network. This service can also be used to re-route a call to another endpoint if a called endpoint is unavailable. In addition, a gatekeeper capable of routing H. For instance, if a call is routed through a gatekeeper , that gatekeeper can then re-route the call to one of many gateways based on some proprietary routing logic. While a gatekeeper is logically separate from H. Gatekeeper is not required in an H. However, if a gatekeeper is present, terminals must make use of the services offered by gatekeepers RAS defines these as address translation, admissions control, bandwidth control, and zone management.

Gatekeepers can also play a role in multipoint connections. To support multipoint conferences, users would employ a Gatekeeper to receive H. When the conference switches to multipoint, the gatekeeper can redirect the H. Gatekeeper need not process the H.

LANs which contain Gateways could also contain a gatekeeper to translate incoming E. Because a Zone is defined by its gatekeeper , H. Under H. The MC handles H. The MC also controls conference resources by determining which, if any, of the audio and video streams will be multicast. The MC does not deal directly with any of the media streams. MC and MP capabilities can exist in a dedicated component or be part of other H. A soft switch includes some functions of an MP. An access server, also sometimes referred to as a media gateway controller, includes some of the functions of the MC.

Approved in January of , version 2 of the H.

EP2317710A2 - Voice over data telecommunications network architecture - Google Patents

The most significant advances were in security, fast call setup, supplementary services and T. A web interface can be provided for a business customer to manage its accounts. The business customer can use the web interface to make additions, deletions, changes, and modifications to PAC translations without involvement of a carrier's customer service department.

An example of call processing using PACs follows. Basic toll-free service supports e. SCP b can then attempt to route the call using a route plan or trigger plan that has been defined for that Toll Free dialed number. SCP b can have several possible responses to a soft switch routing request, see Table 10 above. Using the subscriber routing option described in the previous paragraph SCP b can return a number translation for the Toll Free number. Alternatively, SCP b can return a circuit identifier. SCP b usually returns a circuit identifier when the termination is a dedicated trunk to a customer premise equipment CPE.

Then if SCP b determines that it can not route the call or has determined to block the call per the route plan , SCP b returns a 'route to resource' response to Soft-Switch with an announcement identifier. In this case Soft-Switch can connect the calling party with Announcement Server for the playing of an announcement and then disconnect the caller. The configuration server will now be described in greater detail with reference to FIG. Configuration server supports transaction requests to a database containing information needed by network components. Configuration server supports queries by voice network components during initialization and call processing.

The data contained within configuration server databases can be divided into two types. The first type of data is that used to initialize connections between components. The second set of data can be categorized as that data needed by soft switch for use during call processing. This type of data includes customer and DAL profiles.

This information can include information describing class of service restrictions and account code settings. The database of configuration server contains voice network topology information as well as basic data tables necessary for soft switch call processing logic. Configuration server is queried by soft switches at start-up and upon changes to this information in order to set up the initial connections between elements of telecommunications network Configuration server is also queried by soft switches in order to configure initial settings within soft switch Configuration information for AGs and TGs includes: number and configuration of bays, modules, lines and channels; relationship of modules, line and channels to OPC, DPC and CIC values; and relationship of module, line and channels to trunk groups.

Tables necessary to support class of service restrictions include: LATA tables; state tables; and blocked country code tables. Configuration server also contains information related to customer trigger plans and service options. Customer trigger plans provide call processing logic used in connecting a call. Configuration server information is queried during call processing to identify the service logic to be executed for each call. The information that soft switch uses to look-up customer profile data is the ANI, trunk ID or destination number for the call.

The information that will be returned defines the call processing logic that is associated with ANI, trunk ID or destination number or trunk group. Table 12 includes an example of a customer profile query. Trunk ID. Table 13 includes an example of a customer profile query response provided by configuration server Configuration server interfaces to components. Configuration server receives provisioning and reference data updates from data distributor of provisioning component Configuration server also provides data to soft switch for call processing.

Configuration server is used by soft switch to retrieve information necessary for initialization and call processing. Information that soft switch retrieves from configuration server during a query is primarily oriented towards customer service provisioning and gateway site , port configuration. Configuration server uses a separate physical interface for all SNMP messages and additional functions that may be defined.

Examples of additional functions that may be defined include provisioning, updating, and the passage of special alarms and performance parameters to configuration server from the NOC. In an alternative embodiment, the functionality of configuration server can be combined with that of route server in a single network component. In an additional embodiment of the invention the functions of either or both of CS and RS can be performed by application logic residing on soft switch Route servers a and b are connected via redundant connections to soft switches a, b and c.


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Soft switches a, b and c are in turn connected to gateway sites via data network not shown. For example, soft switch a is in communication with TG a and TG b. Similarly soft switch b is in communication with AG a and TG a. Soft switch c is in turn in communication with AG b and AG a.

It would be apparent to a person skilled in the art that additional TGs and AGs, as well as other gateway site devices, such as a NAS device can also be in communication with soft switches a, b and c. Route server will now be described in further detail with reference to FIG.

Route server provides at least two functions. Route server performs the function of supporting the logic for routing calls based upon a phone number. This routing, performed by route server , results in the selection of one or more circuit groups for termination. Another function of route server is the tracking and allocation of network ports. As shown in FIG. Therefore, route server tracks port resources for all TGs a, b and a and AGs a, b and a that are serviced by soft switches a, b and c at soft switch site The routing logic accepts translated phone numbers and uses anywhere from full digit routing to NPA-based routing to identify a terminating circuit group.

Routing logic selects the translation based upon the best match of digits in the routing tables. An exemplary routing table is illustrated as Table In Table 14, there are five entries that can match the dialed number "". The first route choice is the one that has a full match of digits with priority one. Since there are two entries with full matching digits, and which are marked as priority one, the load should be distributed as shown in the load column, i. The second route choice is the entry with a full digit match, but marked with the lower priority of two.

The last route choice is the one that has a matching NPA only. In situations where there are multiple route choices for a DDD number i. The factors to be considered in selecting a terminating circuit group include: 1 the percent loading of circuit groups as shown in the load column of Table 14; 2 the throttling use of trunk groups to avoid overloaded networks; 3 the fact that end office trunk groups should be selected before tandem office trunk groups; and 4 routing based upon negotiated off-network carrier agreements.

Agreements should be negotiated with off-network carriers to provide the flexibility to route calls based upon benefits of one agreement another. The following types of agreements can be accounted for: 1 commitments for the number of minutes given to a carrier per month or per year; 2 the agreement that for specific NPA or NPA-NXX sets, one carrier may be preferred over another; 3 the agreement that international calls to specific countries may have preferred carriers; 4 the agreement that intra-LATA or intra-state calls originating for certain areas may have a preferred carrier in that area; and 5 the agreement that extended area service calls may have a preferred carrier.

The logic for route server can include routing for international calls. In the example shown in Table 14, it is possible to have fully specified international numbers, or simply specified routing, for calls going to a particular country. As with domestic numbers, the routing logic should select the table entry that matches the most digits within the dialed number, i. Once a terminating circuit group has been identified, route server needs to allocate a terminating circuit within the trunk group.

The selection of a terminating circuit is made by querying the port status table. Table 15A shows an exemplary port status table. The results of a query to port status Table 15A yields the location and allocation of a circuit. Route server can use algorithms to select circuits within the trunk group. Each circuit group can be tagged with the selected algorithm that should be used when selecting circuits within that group. Example algorithms to select circuits within the group include: 1 the most recently used circuit within a circuit group; 2 the least recently used circuit within a circuit group; 3 a circular search, keeping track of the last used circuit and selecting the next available circuit; 4 the random selection of an available circuit within a circuit group; and 5 a sequential search of circuits within a circuit group, selecting the lowest numbered available circuit.

Table 15A illustrates the association between a circuit group and the selection algorithm that should be used to allocate ports from that group. Table 15B includes the circuit group that a port is a member of , a port identifier, and the current status of that port. The port identifier shown in Table 15B assumes the type of port identification currently used in the IPDC protocol, where the port is represented by a bay, module, line and channel BMLC. It would be apparent to persons skilled in the art that other methods of identifying a port can be used.

The function of route server is to provide least-cost routing information to soft switch , in order to route a call from calling party to called party In addition to providing routing information, route server allocates ports for terminating calls on the least cost routes, e. Route server pair is located at each of soft switch sites , , and services all soft switches a, b, c, a, b, c, a, b and c at that site. Refer to Fig. Route server interacts with at least two other voice network components.

Route server interacts with configuration server Configuration server is used to retrieve initial information on route server start-up to set up the initial routing tables in preparation for receiving requests from soft switches a, b and c, for example. Route server also interfaces with soft switch Soft switch can send route requests to route server that contain either a phone number or a circuit group.

Route server can perform its least cost routing logic to first select a terminating circuit group for the call. Using that circuit group, route server can then select and allocate a terminating circuit. A description of the messages and model of interaction between route server and soft switch follows. Route server is used by soft switch to identify the possible network terminations for a call.

Using this information from soft switch , route server can return the port on an AG , or TG , that should be used to terminate this call. Using this port information, soft switch can then signal the originating and terminating TG or AG to connect the call through data network The route server will now be described further with reference to FIG. In exemplary call flow , the call originates and terminates at different sites, specifically, gateway sites , and Since exemplary call flow originates and terminates at different sites, the cooperation of the originating soft switch and terminating soft switch and route servers , , respectively to identify the terminating circuit.

Portions of the call flow will now be described in greater detail. As depicted in step , for calls arriving on SS7 signal trunks, soft switch receives call arrival notifications in the form of IAM messages. Upon receipt of the IAM message from SS7 GW , soft switch performs some initial digit analysis to determine the type of the call. In step , for calls involving customer features, soft switch can use the ANI of calling party i.

This is done to identify the originating customer's feature set. Each customer's feature set is known as a "trigger plan" for origination of the call. A trigger plan can be thought of as a flowchart which branches based on certain triggering events dependent on the caller's identity. Customer trigger plans reside in a customer profile on configuration server In step , the customer profile database of configuration server returns the customer trigger plan to soft switch Soft switch can perform any processing necessary to implement the customer's specified originating triggers.

Application logic in soft switch can then generate a translated number or an identification of the terminating circuit group for this call. For example, in the case of an call, a translation may be requested as in step of an SCP SCP converts the number into a normal number for termination, and in step returns the number to soft switch In step , in order to translate the translated number or circuit group into an egress port, soft switch makes a route request to route server Upon identifying the terminating circuit group, the route logic queries a circuit group to soft switch mapping table in route logic of route server , to identify the target soft switch that handles the identified termination.

For example, the target soft switch may be soft switch It is important to note that there can be multiple route choices, and therefore there can be multiple soft switches , supporting a single route request. In step , route server responds to soft switch with the terminating circuit group. In this example, the terminating circuit group is included in trunks connected to trunking gateway , which is serviced by a different soft switch namely soft switch than originating soft switch Therefore, route server responds with the terminating circuit group and identifies soft switch as the soft switch that handles that terminating circuit group.

In step , originating soft switch initiates the connection from the origination to the termination, by requesting a connection from the originating trunking gateway Trunking gateway , upon receipt of the set-up request from soft switch , allocates internal resources in trunking gateway TG manages its own ports.

In step , originating soft switch issues a call setup command to terminating soft switch This is the command identified by route server In step , soft switch queries route server to determine the termination port for the call. Specifically, soft switch queries port status of route server The query in step , "passes in" as a parameter the terminating circuit group. In step , route server allocates a termination port and returns the allocated termination port to terminating soft switch In step , terminating soft switch instructs the identified end point i.

Terminating soft switch passes in an IP address and an RTP port corresponding to the port that was allocated by originating TG In step , terminating TG returns the allocated resources for the call to soft switch In step , terminating soft switch returns to originating soft switch the IP address of TG In step , originating soft switch communicates with originating TG in order to inform originating TG of the listed port that was allocated by terminating TG At this point, originating TG and terminating TG have enough information to exchange full duplex information.

In step , originating TG acknowledges the receipt of the communication from soft switch to soft switch Table 16A shows fields that can be included in a route request sent from soft switch to route server The route request can contain either a DDD number or a circuit group that requires routing. The route request message can also contain information about the call, collected from the IAM message, that is necessary to perform routing of this call. The route request message can also contain information about the call, necessary to perform routing of the call, which is obtained from the processing of the call.

For example, in the case of an call, this information can be a translated number. Table 16B shows fields which can be included in a response corresponding to the route response, sent from route server back to soft switch The route response message can contain a plurality of route terminations for the DDD or circuit group that was passed in as a parameter to route server For example, the route response message can include 1 to 5 route choices. Each of the route choices of the route response message can include various fields of information. For example, each route choice can include the following information: the circuit group, the circuit, the outpulse digits, the destination number and the destination soft switch In situations where the selected circuit group is managed by the same route server that serviced the route request, the response for that route can contain all the information about the destination.

This is possible because route server can identify and allocate the circuit within the circuit group. In situations where another route server services the selected circuit group, the response for that route only contains the circuit group and the destination soft switch Originating soft switch can then make a request to terminating soft switch to query the terminating route server for a circuit within the identified circuit group.

The terminating soft switch can then control the termination of the call. Soft switch generates call data. This call data can be collected during call processing. Call data can also be generated by capturing events from other network elements. These network elements include internal soft switch site components and external components. Call data can be collected by a primary and secondary server at each RNECP , using high availability redundancy to minimize the possibility of potential data loss.

Soft switch sites , , are illustrated as including RNE CPs for collecting events and routing events to a master database. Specifically, western soft switch site has soft switches a, b, c communicating via a local area network to RNECPs a, b. RNECPs can include disks , RNECPs a, b can be in direct communication with, as well as can take a primary and a secondary role in communicating with, soft switches a, b, c.

MNEDBs a and b can communicate with one another. MNEDB a uses disks a as primary storage for its database. One or more signaling links can be connected to the same two endpoints that together form a signaling link set. Signaling links are added to link sets to increase the signaling capacity of the link set. In Europe, SS7 links normally are directly connected between switching exchanges using F-links. This direct connection is called associated signaling. This indirect connection is called quasi-associated signaling , which reduces the number of SS7 links necessary to interconnect all switching exchanges and SCPs in an SS7 signaling network.

SS7 links at higher signaling capacity 1. High speed links utilize the entire bandwidth of a T1 1. Currently there are no protocol components that provide OSI layers 4 through 6. The Message Transfer Part MTP covers a portion of the functions of the OSI network layer including: network interface, information transfer, message handling and routing to the higher levels. ISUP is the key user part, providing a circuit-based protocol to establish, maintain, and end the connections for calls.

For each active mobile equipment one signalling connection is used by BSSAP having at least one active transactions for the transfer of messages. In , several SS7 vulnerabilities were published that permitted the tracking of cell phone users. The security vulnerabilities of SS7 have been highlighted in U. The perpetrators installed malware on compromised computers, allowing them to collect online banking account credentials and telephone numbers.

They set up redirects for the victims' telephone numbers to telephone lines controlled by them. Confirmation calls of two-factor authentication procedures were routed to telephone numbers controlled by the attackers. This enabled them to log into victims' online bank accounts and effect money transfers. In March , a method was published for the detection of the vulnerabilities, through the use of open-source monitoring software such as Wireshark and Snort.

Signalling System 7. Get Signalling System 7 essential facts below. View Videos or join the Signalling System 7 discussion. Add Signalling System 7 to your PopFlock. History Signaling System No. Indianapolis: Howard W. Signaling System 7 4 ed. New York: McGraw-Hill. International Telecommunication Union.

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