2 Introduction

09.113GPPSignalling Interworking for supplementary servicesTS

This clause describes general procedure at the MSC/VLR for SS interworking between the A- and D-interfaces.

2.1 MSC/VLR procedures for handling supplementary service signalling received over the A-interface

Upon receipt of supplementary service signalling on the A-interface, the MSC/VLR shall:

– perform any internal SS checks or procedures appropriate to the signal (see clauses 4 and 5);

– if necessary request access to the HLR over the D-interface using the procedures defined in this specification and MAP, GSM 09.02;

Рuse the version indicator received from the MS to set up the right AC context name towards the HLR (see clause 3). The version indicator is described in GSM 04.10 and GSM 04.80. AC names are defined in GSM 09.02;

– perform mapping between layer 3 messages on the radio path and TC transaction sublayer messages as required (see clause 3).

2.2 MSC/VLR procedures for handling supplementary service signalling received over the D-interface

Upon receipt of supplementary service signalling on the D-interface, the MSC/VLR shall:

– perform any internal SS checks or procedures appropriate to the signal (see clauses 4 and 5);

– handle any information elements according to the screening indicator procedure as described in GSM 04.10;

– perform mapping between TC transaction sublayer messages and layer 3 messages on the radio path as required (see clause 3).