ForwardAccessSignalling-Arg Message
This service is used between MSC-A and MSC-B (E-interface) to pass information to be forwarded to the A-interface or Iu-interface of MSC-B.
The MAP_FORWARD_ACCESS_SIGNALLING service is a non-confirmed service Supplier is MSCB if Consumer is MSCA. This is a comsumer invoke.
Reference: TS 29.002-f30