GA SMT ALTDEV EXCURSION FROM CLRNC ALT IN RESPONSE TO WRONG CALL SIGN.

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FLYING AN SMA TYPE A FROM ALN TO RFD IN OCT; MY ACFT WAS REFERRED TO AS 'TYPE B (MY CALL SIGN)' A 'TYPE C (MY CALL SIGN)' AND A 'TYPE A (MY CALL SIGN).' EACH TIME THE ACFT TYPE WAS INCORRECTLY REFERRED TO I RESPONDED WITH THE FLT INSTRUCTION GIVEN AND 'TYPE A (MY CALL SIGN).' AFTER SEVERAL STEP DOWNS I WAS ASSIGNED 5000 FT AND TOLD TO INTERCEPT THE LOC AND FOLLOW IT INBOUND. 12 MI FROM THE OM; CENTER ISSUED THE INSTRUCTION 'TYPE D (MY CALL SIGN) DSND TO 2500 FT.' I ANSWERED 'TYPE A (MY CALL SIGN)' AND BEGAN MY DSCNT. APPROX 1 MIN LATER CENTER CALLED 'TYPE A (MY CALL SIGN) CLRED FOR ILS 36 INTO ROCKFORD'. I RESPONDED 'TYPE A (MY CALL SIGN) CLRED FOR THE APCH.' AT THAT TIME I WAS AT 3800 FT. CENTER THEN CALLED BACK 'TYPE A (MY CALL SIGN) YOU WERE ASSIGNED 5000 FT.' I RESPONDED 'TYPE A (MY CALL SIGN) WAS INSTRUCTED TO DSND TO 2500.' CENTER THEN STATED 'YOU HAD CONFLICTING TFC BELOW YOU.' CENTER THEN HANDED ME OFF TO ROCKFORD APCH. ROCKFORD APCH THEN REFERRED TO MY ACFT AS 'TYPE E (MY CALL SIGN).' THE FLT THEN CONTINUED DOWN THE ILS; TO A SUCCESSFUL LNDG. NO EVASIVE ACTION WAS NECESSARY OR CONFLICTING TFC OBSERVED. DURING THIS 50 MIN FLT; MY ACFT WAS CORRECTLY IDENTED AS A TYPE A MANY TIMES; HOWEVER; IT WAS ALSO CALLED A TYPE B; A TYPE C; A TYPE D; AND A TYPE E. POSSIBLE THE ACFT TYPE DATA WAS INCORRECTLY ENTERED INTO THE COMPUTER. I ANSWERED EACH CALL WITH MY ACFT TYPE AND CALL SIGN AND EACH ANSWER WAS ACKNOWLEDGED. HAVING MY ACFT SO MANY TIMES MISIDENTED ON 1 FLT I WAS LISTENING CLOSELY FOR MY CALL SIGN. I AM CERTAIN CENTER ISSUED THE INSTRUCTIONS FOR DSCNT TO 2500 FT TO MY CALL SIGN BUT PRECEDED IT WITH THE ACFT TYPE; TYPE D. I ANSWERED WITH MY CORRECT ACFT TYPE AND CALL SIGN AND RECEIVED NO CORRECTION FROM CENTER. IN HINDSIGHT I FEEL I SHOULD HAVE TAKEN TIME TO CLARIFY CENTER'S INSTRUCTIONS AND CONFUSED ACFT TYPE WITH CALL SIGN. IN A BUSY ENVIRONMENT; A PLT IS HESITANT TO TIE UP THE FREQ AND MUST OFTEN WAIT BEFORE A PAUSE ON THE FREQ IS AVAILABLE TO CLARIFY INSTRUCTIONS. EXPECTATION WAS ALSO A FACTOR IN THIS CIRCUMSTANCE. THE ILS 36 APCH CHART FOR ROCKFORD SHOWS 2500 FT AS THE ALT UNTIL ESTABLISHED ON THE LOC. AS I WAS RAPIDLY APCHING THE OM I ANTICIPATED MY NEXT CLRNC TO BE TO 2500 FT. UPON HEARING MY CALL SIGN; EVEN THOUGH IT WAS WITH THE WRONG ACFT TYPE; IT WAS A LOGICAL CLRNC.