scope:

Introduction

This supplement to American National Standard for Telecommunications - Integrated services digital network (ISDN) - Multi-level precedence and preemption (MLPP) service capability, ANSI T1.619-1992, revises the standard so that the exchange-to-exchange signaling is consistent with ITU-T Recommendations Q.955.3 (1993) and Q.735.3 (1993), which were approved after the publication of ANSI T1.619-1992. The significant changes are in the following areas:

- The use of Cause value #45 with a location code of other than 0110 to indicate preemption without circuit reservation is changed to Cause value #8;

- The use of Cause value #45 with a location code of 0110 to indicate preemption with circuit reservation for reuse is changed to Cause value #9;

- Cause value #46 is in codeset 0 instead of codeset 5;

- The MLPP Service Domain code format is changed from a 7-bit field in the Precedence level information element (for DSS1) and in the Precedence parameter (for SS7) to a 3-octet parameter for both DSS1 and SS7;

- The MLPP Service Domain is prefixed with a 2-octet Network Identity (NI) in the Precedence level information element (for DSS1) and in the Precedence parameter (for SS7).

Some other minor errors are also corrected.

These changes result in a protocol that is incompatible with that which was described in ANSI T1.619-1992. Implementors of the protocol described in the original ANSI T1.619-1992 or of that described in this supplement should be aware of this incompatibility and are cautioned to determine the compatibility of interconnecting equipment.

Specifically, the following changes should be made to ANSI T1.619-1992:

In clause 2, change references to the new editions as follows and delete footnote 1:

ANSI T1.113-1992, Telecommunications - Signaling system no. 7 (SS7) - Integrated services digital network (ISDN) user part

ANSI T1.114-1992, Telecommunications - Signaling system no. 7 (SS7) - Transaction capability application part (TCAP) user part

Add the following reference to clause 2:

ITU-T Recommendation Q.850 (1993), Usage of cause and location in the DSS1 and the SS7 ISDN user part