What was found
TRIED TO TRANSMIT ON BOTH SATCOM RADIOS WITHOUT SUCCESS. KEPT GETTING RECORDED MESSAGE STATING IT WASN'T A TOLL FREE CALL. COULD NOT COMPLETE CALL TO DISPATCH. DISPATCH TRIED TO CALL US AND COULD NOT CONNECT. ACFT GROUNDED. PERFORMED SATCOM COMMUNICATION SYSTEM TEST IAW AMM 23-25-00, STEPS 1, AND 2. BOTH INCOMING AND OUTGOING CALLS WERE LOUD AND CLEAR. ACFT OKAY FOR CONTINUED SERVICE.