GMDSS f77 routine and safety usage procedure?

A)-YOUR INMARSAT FLEET-77 IS SET TO AOR BAND CES SOUTHBURY , STATE THE OPERATIONAL PROCEDURE THAT YOU WOULD ADOPT TO ASK FOR MEDICAL ADVICE VIA TELEPHONE VIA GOONHILLY CES
b)-WHAT STEPS WILL YOU TAKE TO ENSURE THAT YOUR VESSEL WILL BE CAPABLE OF RECEIVING REPLIES TO THE MEDICAL ADVICE  REQUESTED ABOVE  EVEN IF ENGAGED IN SOME OTHER ROUTINE COMMUNICATION.