MD80 SPD DEV AT MMX.

Narrative

APCHING MEXICO CITY; WE WERE HANDED OFF TO; AND CHKED IN WITH EITHER MONTEREY OR MEXICO CITY CTR (I DID NOT NOTICE DUE THE CONFUSION THAT CONTINUED UNTIL WE XFERRED TO APCH CTL AT MEXICO CITY). WE AWAITED DSCNT CLRNC AND REALIZED CTR WAS CALLING US -- ONLY BY A DIFFERENT CALL SIGN. WE ARE REFERRED TO AS ACR AND THIS CTLR WAS FRANTICALLY CALLING BY PHONETIC ALPHABET. WE CALLED AND ASKED IF HE WAS TRYING TO REACH US. HE SAID 'ACR DSND TO XXXXX FT.' WE REPLIED 'ROGER; ACR DSNDING TO XXXXX FT.' HE THEN SAID TWICE 'PAY ATTN!' THEN HE ASKED US TO VERIFY WHAT OUR CALL SIGN WAS. WE REPLIED. HE THEN SAID 'THAT IS NOT RIGHT. I DON'T THINK THAT IS YOUR CALL SIGN. PAY ATTN!' THEN HE SWITCHED TO CALLING US BY A DIFFERENT CALL SIGN. DUE TO THE CONFUSION; OUR DSCNT WAS STARTED LATE; AND IN AN ATTEMPT TO CROSS A PARTICULAR VOR AT 13000 FT OR SO; WE KEPT OUR SPD AT 320 KTS. AT ABOUT 15000 FT THE CTLR CAME BACK AND ASKED OUR SPD. I REPLIED '320 KTS' AND INSTANTLY REALIZED WE HAD VIOLATED MEXICO'S SPD LIMIT OF 250 KTS BELOW 10000 FT AGL; OR IN THIS AREA; APPROX 16000 FT MSL. MY COPLT AND I FELT HE ASKED THIS AS AN ENTRAPMENT; AS IF TO VERBALLY VERIFY OR CATCH US IN A VIOLATION. THE WRONG USE OF CALL SIGNS AND A CONFRONTATIONAL ATTITUDE DISTR ME FROM MY PRIMARY MISSION. BOTH MY COPLT AND I ARE RELATIVELY NEW ON THE MEXICO RUN. P.S. WHEN WE CHANGED FREQS; MEXICO CITY WAS VECTORING A SIMILAR ALPHA NUMERIC FLT! CONFUSION?