SendEndSignal-Arg Message
This service is used between MSC-B and MSC-A (E-interface) indicating that the radio path has been established by MSC-B to the MS.
MSC-A retains then the main control of the call until it clears. The response is used by MSC-A to inform MSC-B that all resources for the call
can be released in MSC-B, either because the call has been released in MSC-A or because the call has been successfully handed over or relocated
from MSC-B to another MSC. This is a supplier invoke.
Reference: TS 29.002-f30