scope:

This Standard ECMA-I06 defines the Layer 3 protocol for signalling for the purpose of circuit-switched call control at an interface at the S reference point between a Terminal Equipment (TE) and a Private Telecommunication Network (PTN).

A PTN consists of one or more interconnected Private Telecommunications Network Exchanges (PTNX), and therefore an interface at the S reference point is actually between a TE and a PTNX. The S reference point is defined in Standard ECMA-133. Other ECMA Standards will define protocols for use at other reference points, notably the O reference point between two interconnected PTNXs within a PTN.

This Standard defines the Layer 3 protocol for circuit-switched call control, i.e., for the support of circuit mode basic bearer services used either on their own or in support of teleservices. The basic bearer services and teleservices supported are those specified in Standard ECMA-142. Other ECMA Standards will define additions to the ECMA-I06 protocol for the support of supplementary services.

Service specifications are produced in three stages and according to the method specified in ENV 41005. This ECMA Standard is an output from stage 3, the definition of signalling protocols, and therefore satisfies the requirements identified by the stage I and stage 2 specifications in Standard ECMA-142.This Standard is applicable to user accesses of PTNXs and to TEs which are intended for connection to PTNs.

The conveyance of non-standardized (e.g. manufacturer-specific): .. information in Standard ECMA-I06 messages is outside the scope of this Standad Annex D discusses ways in which this can be achieved.