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E1ITUTSSNo7ISUPTelesis systems support ISUP ETSI EN 300 356 version 3 and ITU-T recommendations. Telesis systems are integrated systems that include both a voice switch and an SS7 switch. A Telesis system may serve as two types of signaling points in an SS7 network: As an SSP, the Telesis system responds to all calls bound for known signaling points by looking at its routing table to determine how to route each call and then sending a message to the destination using the ISUP protocol. A unique feature of the Telesis system is that multiple SPs may be defined in a single system. So, several OPCs may exist in the same system. This results in the combining of both SSP and STP functions in a single Telesis system. As an STP, the Telesis system acts as a router or gateway in an SS7 network. ISUP messages are routed based on Global Title or DPC or Calling Party Information Element parameters. With Telesis`s OPC translation feature, ISUP traffic flowing in a private SS7 network may be routed to the public SS7 network. Layers and Options The physical layer (MTP-1) of SS7 signaling in Telesis systems is an E1 (ITU-T G.703) interface. Options for the data link layer (MTP2) include programmable basic error correction methods or PCR (Preventive Cyclic Retransmission). For the network layer (MTP3), SLTM periods are set as desired, and acknowledgment of test messages (SLTA) is automatic. OPC and DPC as well as CIC prefixes can also be set easily. Several parameters in ISUP messages are programmable. Some of these are:
Physical Links Telesis systems support both terrestrial and satellite links. For terrestrial links, BEC function is utilized. Due to the delay arising in satellite links, the PCR (Preventive Cyclic Retransmission) error correction function is used. Link and Linkset Configuration The link is an existing E1 interface on the Telesis system. Any 64 kbps channel on an E1 (except channel 0) is programmable as the signaling path. Several links may be grouped into a linkset sharing a common signaling path. Each linkset has its own OPC and DPC. In the same Telesis system, there may be several linksets, each having an individual OPC. Furthermore, selected channels of every E1 link can be programmed as unavailable for outgoing traffic, thereby yielding fractional E1 connections. Route and Routeset Configuration In a Telesis system, each link and/or linkset may have its own route number. It is possible to define numerous distinct routes. A given route to a particular destination and its accompanying alternate routes are grouped in a routeset. Each route in a routeset has a priority order. Routing to the next priority alternate route is possible in the event that a route becomes unavailable. Furthermore, it is possible to define which release causes stated in ISUP messages will lead to the alternate routes being used. Message Routing ISUP message routing is based on dialed digits (Global Title). As an SSP, the Telesis system converts dialed digits from a subscriber`s line to SS7 signaling messages. As an STP, the Telesis switch may realize routing according to:
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