A.4 AssistRequestInstructions operation

29.0783GPPCAMEL Application Part (CAP) specificationCustomised Applications for Mobile network Enhanced Logic (CAMEL) Phase XRelease 17TS

If an ISUP IAM is received at an assisting SSP containing an assisting gsmSSF or at an IP containing a gsmSRF, then an AssistRequestInstructions operation is sent to the gsmSCF. The correlationID parameter in the AssistRequestInstructions operation can contain:

a) the CorrelationID digits extracted from the ISUP IAM Called Party Number,

b) the whole Called Party Number received in the ISUP IAM (CorrelationID digits extracted at gsmSCF),

c) the contents of the ISUP IAM CorrelationID parameter.

In the case where the gsmSCF and the assisting gsmSSF are both in the HPLMN and ISUP 97 is supported then any of these mechanisms may be used.

In the case where the gsmSCF and the assisting gsmSSF are both in the HPLMN and ISUP 97 is not supported then mechanisms a) and b) may be used.

In the case where the gsmSCF is in the HPLMN and the assisting gsmSSF is in the VPLMN then only mechanism b) may be used when an all-ISUP 97 signalling path cannot be guaranteed. Mechanism a) may be used if bilateral agreements on the format of the information transferred in the ISUP IAM Called Party Number are defined between the HPLMN and the VPLMN.

In the case where the gsmSCF is in the HPLMN and the assisting gsmSSF is in the VPLMN then mechanism c) may only be used if an all-ISUP 97 signalling path can be guaranteed between the HPLMN and the VPLMN.