As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEVERAL ATTEMPTS TO MAKE/RECEIVE SAT CALLS BUT UNABLE TO HEAR DISPATCH ON BOTH 1 & 2, VOLUMES SET HIGH. DISPATCH HEARD ME. GROUNDED - YES. REF B737-800 FIM TASK 23-15-00-23-801, VERIFIED BOTH SATCOM OPS CHECKED LOUD AND CLEAR WITH DISPATCH DIR. NO DEFECTS HIST FOR LAST 30 DAYS.