RPTR TOOK ANOTHER FLT'S CLRNC TO CROSS RWY 16L AND RWY 17. THERE WAS AN ACFT ON THE LNDG ROLL THE RPTR TAXIED IN FRONT OF. THE RPTR READ BACK THE CLRNC TO CROSS BUT THE READBACK DID NOT SHOW UP ON THE PLAYBACK OF THE TWR TAPE.

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WE WERE REPOSITIONING FROM W SIDE TO E SIDE OF ARPT; HOLDING AT HOTEL 2; RWY 16L. WE RECEIVED A XING CLRNC 'CROSS RWY 16L ACFT HOLDING IN POS; HOLD SHORT RWY 17; MONITOR TWR 118.3.' I READ THAT BACK AND WE CROSSED. GOT ANOTHER CLRNC TO CROSS RWY 17 AND CONTACT GND 121.65. FROM GND WE GOT TAXI CLRNC TO PARKING PLUS TO OUR ASTONISHMENT; A REQUEST TO PHONE THE TWR. APPARENTLY; UPON CALLING; WE HEARD WE HAD ILLEGALLY CROSSED THE RWY 16L ON A CLRNC FOR ANOTHER ACFT WHICH WAS HOLDING SHORT AT HOTEL 10. ANOTHER ACFT HAD JUST LANDED SO HE COULD CROSS THE RWY; HOWEVER; WAS STILL IN THE ROLLOUT; SO WE COULDN'T CROSS YET. ALTHOUGH WE DID SEE LIGHTS IN THE DISTANCE; WE FIGURED IT WAS THE ACFT HOLDING IN POS AND SINCE TWR NEVER REACTED TO OUR READBACK WE WEREN'T ALARMED AND JUST CROSSED. THEY LISTENED TO THE TAPES AND COULDN'T FIND A TRACE OF OUR READBACK; SO EITHER OUR RADIO FAILED MOMENTARILY OR THE OTHER ACFT RADIO OVERPWRED OURS COMPLETELY. IN ANY CASE; NOBODY KNEW WE WERE INTENDING TO CROSS AND SINCE WE DIDN'T HEAR ANYTHING NEGATIVE AFTER OUR READBACK; ASSUMED WE WERE DOING THE RIGHT THING BY XING THE RWY UNAWARE OF OUR MISTAKE.