AN NORDO A320 EXPERIENCED A DISABLED ACARS BECAUSE THE SCAN MASK FREQ SELECTION WAS IMPROPERLY SET.

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DURING CRUISE AT FL350 A BLEED-THROUGH OCCURRED ON THE #1 RADIO. WE THEN REALIZED WE HAD NO COM WITH ATC FOR AN UNKNOWN PERIOD OF TIME. CONTACT WAS ESTABLISHED WITH CTR AFTER NUMEROUS TRIES. WE WERE QUERIED AS TO COCKPIT SECURITY AND FLT SECURITY. A MESSAGE WAS SENT TO DISPATCH VIA ACARS EXPLAINING THE SIT AND A PROMPT RESPONSE WAS RECEIVED. THE ACARS HAD NOT BEEN RECEIVING AND WE HAD A POSSIBLE TOTAL COM FAILURE WITH NO COCKPIT INDICATIONS. DURING THE APCH PHASE OF THE FLT WE EXPERIENCED SEVERAL PROBS COMMUNICATING WITH NORCAL APCH DUE TO RADIO SQUELCH BLEED THAT SOUNDED SIMILAR TO AN ACARS XMISSION. AFTER A POSTFLT DISCUSSION WITH MAINT; IT WAS FOUND THAT THE COM SYS SCAN MASK WAS SET FOR THE CARIBBEAN/MEXICO AND NOT THE CONTINENTAL UNITED STATES; POSSIBLY EXPLAINING THE LACK OF RECEPTION OF NUMEROUS MESSAGES SENT BY DISPATCH TO CALL ATTN TO OUR NORDO STATUS. DURING OUR NO COM PERIOD; WE RECEIVED NO RADIO; SELCAL OR ACARS XMISSIONS. NUMEROUS PEOPLE MET THE ACFT AT THE GATE. WE HAD 2 FAM'S ON THE FLT AND WE WERE ASKED WHY THE FAM'S WERE UNABLE TO BE CONTACTED AIRBORNE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THE ACARS XMIT AND RECEIVE FREQ OPTIONS (SCAN MASK) ARE NORMALLY AUTOMATICALLY SET BY THE ACARS SOFTWARE DEPENDING ON THE ACFT'S GEOGRAPHICAL LOCATION. HOWEVER; IF THE ACARS FREQ SELECTOR IS NOT IN AUTOMATIC THE ACARS DATA FREQS ARE LIMITED TO THE LOCATION MANUALLY SET; IE; CONTINENTAL UNITED STATES; EUROPE; LATIN AMERICAN AND CARIBBEAN. BECAUSE THE RPTR'S ACFT'S FREQ SELECTION (SCAN MASK) WAS SET MANUALLY TO LATIN AMERICA/MEXICO; THE ACARS OVER THE CENTRAL UNITED STATES COULD NOT RECEIVE MESSAGES FROM THE COMPANY'S DISPATCH WHO WERE ATTEMPTING TO GIVE THEM A VHF FREQ TO TALK TO ZLC. THE CREW; HOWEVER; KNEW NOTHING ABOUT THE SCAN MASK AND; THEREFORE; ASSUMED AN ACARS MALFUNCTION. THERE WAS ALSO A CONCERN AMONG THE GND TSA PERSONNEL ABOUT THE SECURITY OF THE FLT BECAUSE OF THE NORDO STATUS AND THE FACT THAT THE TSA FAM AGENTS WHO WERE ALSO ON THE ACFT COULD NOT BE CONTACTED. TSA BRIEFED THE CREW ABOUT THEIR STATUS.