As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COULD NOT TRANSMIT ON SAT RADIO. WHEN MAKING CALL TO DISPATCH, I COULD HEAR THEM ANSWER, BUT THEY COULD NOT HEAR ME.THIS WAS THE CASE FOR BOTH SAT #1 AND SAT #2. TRIED 4 TIMES ENROUTE AND THEN AGAIN GOING INTO KSAN. SAME RESULT. GROUNDED - YES. PERFORMED OPS TEST OF SATCOM ON BOTH CAPT & FO SIDE. REF B737-900 AMM 23-15-00-730-801. OPS TEST GOOD.