As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO RECEIVE VOICE COMMS ON SAT 1 OR 2. CALLING PARTY COULD HEAR US, BUT WE COULDN'T HEAR THEM. ACFT GROUNDED. UNABLE TO DUPLICATE. REMOVED, REPLACED, AND TESTED SATCOM TRANSCEIVER IAW AMM 23-15-00. TEST PASSED. ETOPS SIGNIFICANT SYSTEM GROUND VERIFICATION SUCCESSFUL.