B757-200 CREW AND ANOTHER SIMILAR CALL SIGN ACFT WERE MIXED UP BY THE CTLR AND CLBED TO AN ALT MEANT FOR THE OTHER ACFT.

Narrative

FLT FROM ATL TO CMH AT FL290. FLT PLAN SAID TO ASK FOR HIGHER ALT IF ATC WOULD ALLOW; BECAUSE FL290 IS USUALLY THE HIGHEST DUE TO TFC. LEVEL AT FL290; WE ASKED ATC FOR FL330 AND HE SAID; 'IT IS JUST COMING NOW; YOU'RE CLRED TO FL330.' WE CLBED QUICKLY TO GET TO A SMOOTHER RIDE. SHORTLY AFTER; ANOTHER ACFT WITH A SIMILAR CALL SIGN CALLED LEVEL AT FL290 AND WANTED HIGHER. ATC SOUNDED A BIT CONFUSED AND THOUGHT HE HAD GIVEN THE OTHER ACFT THE CLB. WHEN WE ASKED ATC IF WE SHOULD HAVE BEEN AT FL330; HE STATED; 'YOU TOOK THE OTHER ACFT'S CLRNC TO FL330.' WE THEN CLARIFIED THAT HE DID INDEED CLR US TO FL330 AND WERE TOLD TO STAY THERE. WE ARE 100% CERTAIN HE CLRED US AND THAT HE MEANT TO GIVE IT TO THE OTHER ACFT. HE SAID THERE WAS NO PROB AND NO CONFLICTS. NO RPTS WOULD BE FILED. NOTE: ALWAYS DOUBLECHK IF SIMILAR CALL SIGNS AND FLT PLAN SAYS HIGHER ALT WOULD BE UNLIKELY. SUPPLEMENTAL INFO FROM ACN 612078: OUR CALL SIGN WAS VERY SIMILAR TO ANOTHER CALL SIGN. FL290 WAS OUR FILED ALT BUT WE WANTED TO GO HIGHER FOR SOME WX IN THE AREA. THE CTR CTLR CLRED US TO FL330; MISTAKENLY BELIEVING WE WERE THE OTHER ACFT WITH THE SIMILAR CALL SIGN. AFTER WE REACHED FL330; THE CTLR QUERIED THE OTHER ACFT AS TO WHY HE WASN'T CLBING. HE RPTED THAT HE HAD RECEIVED NO CLRNC TO CLB. WE THEN CALLED THE CTLR AND TOLD HIM WE WERE AT FL330 AND AN ACFT CALL SIGN WAS THE ONE THAT HAD RECEIVED THE CLRNC. THERE WAS NO TFC CONFLICT AND THE CTLR FIGURED OUT HIS MISTAKE IMMEDIATELY. SPECIAL ATTN NEEDS TO BE PAID WHEN TWO SIMILAR CALL SIGNS ARE ON THE AIR.