As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNABLE TO ESTABLISH CONTACT ON SATCOM 1 OR 2, CALLING PARTY ANSWERS BUT UNABLE TO HEAR US. ACFT GROUNDED. GROUND VERIFICATION PASSES ON BOTH SAT 1 & SAT 2 WAS ABLE TO ESTABLISH CONTACT WITH DISPATCH, ON SAT 1 & 2. ACCOMP. SAT COMM. VOICE TEST OUT GOING CALLS AND INCOMING CALLS FOR BOTH NR 1 & NR 2 SAT REF MM 23-15-00-730-801.