ACR FLT CREW READBACK 1600 FT ON CLEARANCE RATHER THAN THE 16000 FT THEY WERE CLEARED TO.

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FO PICKED UP CLRNC. READ BACK '...AF 1600 FT FL360 10 MINS AFTER....' WHEN WE TOOK OFF WE TURNED TO A TWR ASSIGNED HDG OF 030 DEGS AND THE FO CONTACTED DEP AND ATC SAID 'THROUGH 2000 FT CLRED DIRECT TO LEE COUNTY.' THE FO ASKED; AT MY DIRECTION; TO CLARIFY THE ALT CLRED TO. THE CTLR RPTED BACK 16000 FT. THIS LEAD US TO BELIEVE THAT THE ORIGINAL CLRNC SHOULD HAVE BEEN 16000 FT AS OPPOSED TO 1600 FT. WE LEVELED AT 1600 FT FOR PROBABLY 10 SECONDS AND THEN CONTINUED THE CLB TO 16000 FT. WE THEN CLARIFIED THE CLRNC WITH ATC AGAIN TO BE SURE WE BOTH HEARD DIRECT LEE COUNTY AFTER THE CONFUSION. THE CTLR NEVER MENTIONED ANYTHING RELATING TO AN ERROR OR LOSS OF SEPARATION. WE LOOKED AT OUR PAPERWORK AND THE FO DID INDEED WRITE DOWN 1600 FT AND READ BACK 1600 FT. WE FIGURED OUT SOMETHING WAS WRONG WHEN TOLD TO GO DIRECT TO LEE COUNTY AFTER PASSING 2000 FT WHEN WE UNDERSTOOD OUR CLRNC TO BE 1600 FT. I AM NOT QUITE SURE WHY THE EVENT OCCURRED. EITHER CLRNC DELIVERY SAID 1600 FT OR THE FO THOUGHT HE SAID 1600 FT WHEN HE REALLY SAID 16000 FT. EITHER WAY; HE WROTE DOWN AND READ BACK 1600 FT.