What was found
"SAT" SELECTION INTERMITTENT ON NR 1 CDU. TRIED SATCOM LOCKUP PROCEDURE IN QRH. SAT RETURNED BUT DISAPPEARED AGAIN. SAT SELECTION AVAILABLE ON NR 2 CDU TO DIAL. FIRST CONTACT WITH MEDLINK. ON SECOND ATTEMPT, COULD HEAR MEDLINK BUT THEY COULD NOT HEAR US. THEN DISCONNECTED. TRIED TO CALL ON BOTH SATCOM 1 AND SATCOM 2. BOTH UNSUCCESSFUL. GROUNDED - YES. FOUND SATCOM PROMPT PRESENT AND NOT INTERMITTENT ON BOTH MCDU'S. SATCOM BITE INDICATES NO FAULTS. SUSPECT KNOWN NUISANCE FAULT. ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL.