CLRNC REPLY TO WRONG CALL SIGN. BEGAN UNCLRED DSCNT OUT OF ASSIGNED ALT.

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THIS FLC RECEIVED A CLRNC THAT WE UNDERSTOOD TO BE TO CROSS WHIGG AT 10000 FT. AT THIS TIME THE ACFT WAS APCHING THE POINT AT WHICH A NORMAL IDLE DSCNT WOULD ENABLE XING WHIGG AT 12000 FT. CREW WAS EXPECTING FURTHER DSCNT CLRNC TO CROSS WHIGG AT 12000 FT AS PER THE CRESO STAR; THEREFORE THE CLRNC WAS READ BACK CONCISELY TO ATC; INCLUDING ACFT CALL SIGN. WITH NO IMMEDIATE REPLY FROM ATC THAT THERE MIGHT BE ANY ERROR IN THE READBACK; 10000 FT WAS SET INTO THE MCP ALT ALERT WINDOW AND A DSCNT WAS COMMENCED. APPROX 400 FT BELOW FL230 ATC CALLED AND SAID THE 10000 CLRNC WAS FOR ANOTHER ACFT AND FOR US TO MAINTAIN 230 FOR CONFLICTING TFC. AN IMMEDIATE PULL UP WAS INITIATED AND THE ACFT RETURNED PROMPTLY TO FL230. THERE WAS A TCASII TA AFTER THE ATC CALL. NO TCASII RA. CONTRIBUTING FACTORS/PERCEPTIONS: HVY RADIO TFC. MULTIPLE ALT CLRNCS TO MULTIPLE ACFT. CONFLICTING TFC IN THE NORMAL DSCNT PATH OF THE STAR. POSSIBLE CALL SIGN CONFUSION. POSSIBLE CTLR OVERLOAD. POSSIBLE TO PROBABLE RADIO XMITTER CROSS BLOCKING/JAMMING.