As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN MAKING SATCOM CALL ON SAT1 & SAT2, DISPATCH WAS UNABLE TO HEAR US. WE COULD HEAR THEM. ALL BUTTONS PUSHED CORRECTLY. GROUNDED - YES. PERFORMED SATCOM SYSTEM ADJ/TEST REF AMM 23-15-00/501 & NR 1 NR 2 OPS NORMAL. COULD NOT DUPLICATE.