GSM 09.02 - Version 5.3.0 - Digital cellular telecommunications - ETSI

19.6.3 Procedures in the VLR
Process Access Request
Page 509
GSM 09.02 Version 5.3.0: August 1996
When receiving the MAP_PROCESS_ACCESS_REQUEST indication, the VLR acts as described in
clause 21 of this ETS.
Supplementary service invocation
When receiving the MAP_INVOKE_SS indication, the MAP user acts as follows:
- if the operator has barred the subscriber from access to supplementary services, the error "Call
Barred" is returned to the MSC. The parameter "operatorBarring" shall be included with the error;
- if any irrelevant information elements (according to the service description) or invalid information
element values are present in the service request, then the unexpected data value error is returned
to the MSC in the MAP_INVOKE_SS response;
- if the VLR does not support the invoked supplementary service then the VLR shall respond with the
SS Not Available error;
- if the requested supplementary service cannot be invoked by subscriber actions, then the VLR shall
respond with the Illegal SS Operation error;
- if the subscriber is not provided with (i.e. subscribed to) the requested supplementary service, then
the SS error status error (possibly including the SS-Status as parameter) is returned to the MSC in
the MAP_INVOKE_SS response.
If all checks are passed the VLR returns an empty MAP_INVOKE_SS response to the MSC, thus
indicating that the invocation request was accepted.
If at any time during this procedure a MAP_P_ABORT, MAP_U_ABORT, MAP_NOTICE or unexpected
MAP_CLOSE indication concerning the process is received from the MSC, the process terminates. If a
MAP_NOTICE indication was received from the MSC, that dialogue must be aborted by sending a
MAP_U_ABORT request indicating Procedure error towards the MSC. The process terminates.
The invocation procedure in the VLR is shown in figure 19.6.3/1.