FK10 CREW LOST COM WITH ATC.

Narrative

ON FLT INTO CLT HAD CONVERSATION WITH CAPT THAT WE WERE GETTING A LATE DSCNT FOR THE ARR. RECEIVED A FAULT INDICATION ASSOCIATED WITH PRESSURIZATION SYS AND RAN THE PROCS FOR THAT. IN GOING BACK TO THE RADIO/COM PROB IT BECAME EVIDENT THE FREQ WE WERE NOW MONITORING WAS NOT THE CORRECT ONE. RECEIVED ACARS MESSAGE TELLING US TO GO TO A CERTAIN FREQ HOWEVER; THE MESSAGE WAS MISSING SOME CHARACTERS SO WERE UNABLE. TRIED BRIEFLY TO FILL IN FOR THE MISSING CHARACTERS BUT WERE UNABLE TO ESTABLISH PROPER CONTACT. ENDED UP FINDING OUR PRIOR CTR FREQ AND MADE CONTACT WHERE WE WERE SENT TO APCH CTL TO ARRANGE OUR DSCNT. THE COMBINATION OF EVENTS LEFT US AT FL240 TILL WE WERE ABOUT ON TOP OF CHARLOTTE. MY ONLY GUESS IS THAT SOMEWHERE IN THE SCENARIO THE CAPT INADVERTENTLY MOVED THE CTL HEAD ON THE RADIO; AND THE RESULTING FREQ JUST HAPPENED TO LAND ON A CTR FREQ; AND THE ERROR WAS NOT NOTICED. THE PRESSURIZATION FAULT AND THE INCOMPLETE ACARS XMISSION LENGTHENED THE PROCESS. I BELIEVE THAT WE NEVER FELT RUSHED; ONLY FRUSTRATED AT THE INABILITY TO COMMUNICATE WITH THE CTR/APCH CTL.