Lucent Technologies 7820-0802-003 manual Configuring an SS7 signaling gateway, Continuity tests

Signaling System 7 (SS7)

Configuring an SS7 signaling gateway

See MultiVoice for MAX TNT Configuration Guide for a more detailed description of how VoIP calls are processed by IPDC.

Interface between a signaling gateway and TAOS unit

TCP/IP is the transport service used to carry control messages between a signaling gateway and the TAOS unit. The data delivery layer (DDL) uses a TCP/IP socket on both the signaling gateway and TAOS unit. On the signaling gateway side, the DDL is the server that listens for the socket connection and keeps track of the mapping between a TAOS unit and its socket. On the TAOS unit side, the DDL is the client that initiates a socket connection and handles connection establishment, connection recovery, and link selection.

Incoming calls

The ingress central office (CO) switch (see Figure 18-1) processes the incoming call based on the called number, then identifies the TAOS unit as the destination for the call. The SS7 network sends an initial address message (IAM) to the signaling gateway. The signaling gateway informs the TAOS unit that a call will be coming in on one of the IMT channels from the CO switch. The message from the CO switch contains the calling and called party number, the circuit identification code (CIC), and the destination point code (DPC). The signaling gateway sends an address complete message (ACM) to the SS7 network acknowledging that it has received the relevant information to route the call.

The signaling gateway then sends a call origination message to the TAOS unit to establish a path between the ingress switch and the TAOS unit. The TAOS unit sets up the path and then sends an answer message to the signaling gateway so that the signaling gateway can make the proper updates to its resource management database. For a T1 or T3 network, the signaling gateway then sends an answer message to the SS7 network.

Once the path is set up, the TAOS unit accepts the call, off-loading the Internet call from the PSTN to the data network. The data network used to off-load the call can be a Frame Relay, ATM, or IP network.

Continuity tests

A continuity test can be performed at the time of call setup or during testing to verify that the physical link between the CO switch and the TAOS unit is available. The CO switch informs the signaling gateway, which then informs the TAOS unit that it will conduct a continuity test on the circuit. During a call continuity test, the CO switch sends a tone through the physical path to the TAOS unit and receives a tone back from the TAOS unit indicating the continuity of the path.

Configuring an SS7 signaling gateway

The signaling gateway and TAOS unit communicate over a TCP/IP link. The signaling interface can be a single or dual TCP connection between the TAOS unit and signaling gateway. When the interface initializes, it opens TCP connections to the specified addresses and ports of the signaling gateway. The TAOS unit keeps the TCP connections open as long as the unit is operating and the signaling interface is enabled.

18-4 APX 8000/MAX TNT/DSLTNT Physical Interface Configuration Guide