Question: In a Support of Optimal Routeing (SOR) scenario, if GMSCA determines that forwarding a call to LEC would violate charging requirements, what action does GMSCA take with the call?
Option 1: Sends a cancellation request to the originating party.
Option 2: Constructs an IAM using the B subscriber address and sends it to GMSCB for further routeing.
Option 3: Directly forwards the call to LEC without considering charging implications.
Option 4: Returns an error message to the network indicating 'charging requirements not met'.
Explanation: When GMSCA identifies a potential violation of charging requirements for Support of Optimal Routeing by forwarding a call directly to LEC, it initiates an alternative routeing process. This involves constructing an Initial Address Message (IAM) with the B subscriber's address and sending it to another Gateway Mobile Switching Center (GMSCB), allowing for a re-evaluation of the optimal route that adheres to charging specifications, thus ensuring compliance before proceeding with the call setup.