FLT CREW OF B752 DSNDED BELOW CLRED ALT WHEN THEY RESPONDED TO DSCNT CLRNC GIVEN TO FLT WITH SIMILAR SOUNDING CALL SIGN.

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WE WERE IN IND ARTCC AIRSPACE NAVIGATING BTWN 2 LARGE TSTMS WHEN WE RECEIVED CLRNC TO DSND TO FL330. I ACKNOWLEDGED THE CLRNC USING OUR FULL CALL SIGN OF ACR X; SINCE WE HAD BEEN TRAILING A COMPANY FLT ALL THE WAY FROM FLORIDA. PASSING THROUGH FL340; WE RECEIVED THAT WONDERFUL QUESTION; 'ACR X; VERIFY FL350.' THUS BEGAN IMMEDIATE TURNS (TOWARDS THE TSTM; OF COURSE); FURTHER TURNS AND DSCNTS TO AVOID TFC AND CUMULONIMBUS; AND EVENTUALLY WE WERE ON OUR WAY AT FL310. THERE WERE NO 'CLOSE CALLS' AS FAR AS TFC; BUT THE TURNS BOXING US INTO THE WX CREATED HAVOC FOR US AND THE CTLR. THIS IS ANOTHER CLASSIC CASE OF SIMILAR SOUNDING CALL SIGNS CREATING HAVOC. I AM CERTAIN THAT I READ BACK OUR COMPLETE CALL SIGN WITH OUR CLRNC; AND IT WAS SIMPLY NOT CAUGHT. IT WAS NOT AN ILLOGICAL CLRNC FOR US; SO IT RAISED NO CONCERN. MY SUSPICION IS THAT TRAINING MAY HAVE BEEN GOING ON IN OUR SECTOR; SINCE I RECALL THE ORIGINAL DSCNT CLRNC COMING FROM A WOMAN; AND THE LATER QUERY AND SUBSEQUENT VECTORS CAME FROM A MAN. OTHER CONTRIBUTING FACTORS: WE SHOULD HAVE USED GREATER DILIGENCE IN LISTENING. ATC SHOULD HAVE USED CAUTION ALSO (WE WERE ONLY CAUTIONED ABOUT SIMILAR CALL SIGNS FROM 1 CTLR.) BUT; THE BIG CULPRIT IN MY OPINION IS THE USE OF SIMILAR FLT NUMBERS BY SCHEDULING. THIS SHOULD BE AVOIDED DILIGENTLY BY SCHEDULERS WHEN AT ALL POSSIBLE. SUPPLEMENTAL 590331: WE BEGAN OUR DSCNT AS DIRECTED KNOWING THIS IS COMMON FOR ARRS INTO CHICAGO. THEN WE WERE DIRECTED TO SWITCH FREQS TO ANOTHER IND CTR. WHEN CHKING ON THE NEW FREQ; THE MALE VOICE ASKED US WHY WE WERE AT FL330. WE RESPONDED THAT PREVIOUS CTR DIRECTED US. HE RESPONDED THAT WAS FOR ANOTHER ACFT.