FLT CREW OF CRJ-700 RPTS THAT AURAL INTERFERENCE IN VHF COMS CEASED WHEN PAX WERE ASKED TO ENSURE ALL FORMS OF 2-WAY COMS WERE TURNED OFF.

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ON CLBOUT FROM CLT WE HEARD WHAT SOUNDED SIMILAR TO A FAX MACHINE SOUND OR A MODEM SOUND. WE THOUGHT IT WAS JUST AN ANOMALY; BUT IT HAPPENED AGAIN AND AGAIN IN REPETITIOUS INTERVALS. I ASKED THE CAPT WHAT HE THOUGHT; AND HE SAID IT WAS PROBABLY A 2-WAY PAGER BECAUSE A SIMILAR INCIDENT OCCURRED TO HIM A FEW TRIPS AGO. HE FOUND THAT OUT AFTER ASKING A FLT ATTENDANT TO INVESTIGATE THE SITUATION; AND SHE FOUND SOMEONE WAS TYPING MESSAGES ABOVE 10000 FT MSL SO THAT THEY COULD BE SENT UPON LNDG. WE ASKED OUR FLT ATTENDANTS TO TAKE A WALK THROUGH THE CABIN TO SEE IF ANYONE WAS USING ANYTHING OF THE SORT. NONE WERE FOUND AFTER SHE RPTED BACK TO US. HOWEVER THE ANNOYING NOISES STILL CONTINUED. IT WAS ANNOYING AND LOUD ENOUGH TO ALMOST CAUSE US TO ALMOST MISS RADIO CALLS. SO; AN ANNOUNCEMENT WAS MADE TO PLEASE MAKE SURE CELL PHONES AND 2-WAY PAGERS WERE TURNED OFF BECAUSE IT WAS INTERRUPTING OUR COMS; AND IF THIS WAS NOT DONE WE MAY HAVE TO RETURN TO CLT. AFTER THAT; NEARLY THE ENTIRE PLANE GOT UP TO FIND AND MAKE SURE ALL THE DEVICES WERE TURNED OFF. THE NOISES THEN STOPPED. NO MAKE/MODEL INFO WAS GATHERED BECAUSE: THE FLT ATTENDANTS WERE DOING THEIR SVC; WE WERE STILL CLBING; AND WE ASSUMED NO ONE WAS GOING TO ADMIT GUILT FOR FEAR OF PROSECUTING ACTION. RECOMMENDATION: I WOULD HIGHLY ENCOURAGE MANY MORE IN-DEPTH STUDIES TO BE PERFORMED PRIOR TO ALLOWING CELL PHONES AND OTHER COMS DEVICES TO BE USED ON BOARD ACFT INFLT.