AN ACR MLG LOST COM MOMENTARILY. THERE WAS A CONFLICT WITH A VFR SMA AND SIMILAR SOUNDING ACR CALL SIGNS.

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RAPID DSCNT TO MAKE XING RESTR. TCASII TA AT 12 O'CLOCK 600 FT LOW AND CLBING. I TURNED; CLBED TO MISS CONTACT. AT THE TIME I WAS TURNING; ATC CALLED FOR US TO EXECUTE A TURN TO 330 DEG HDG (APPROX 30 DEG L OF ORIGINAL COURSE). I COULD NOT RESPOND IMMEDIATELY DUE TO FLT DUTIES -- COPLT WAS OFF FREQ GETTING ATIS. ANOTHER COMPANY ACFT WITH SIMILAR CALLSIGN (XXY; OURS WAS XZY) WAS ON FREQ. I REMEMBER ATC GIVING XYY SEVERAL TA'S. POSSIBLY SOME WERE MEANT FOR US. TO MY KNOWLEDGE; WE RECEIVED NO ATC ADVISORIES UNTIL THE 30 DEG TURN. WE MISSED LIGHT TWIN SMA BY 2000 FT. DURING PHONE CALL TO ATC; CTLR SAID HE MADE 3 CALLS TO US WITH NO RESPONSE. (I HAVE NEVER MISSED 3 CALLS IN A ROW!) ATC SUPVR STATED THAT SOME OF OUR COMPANY ACFT ON 127.45 IN THAT AREA HAVE RECEPTION PROBS -- A DEAD ZONE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTING CAPT STATES THAT HE CALLED ZOA WHEN ON THE GND AT SJC. THE ZOA SUPVR TOLD HIM THAT SEVERAL OF HIS ACR ACFT SEEM TO HAVE A COM PROB IN THE SAME GENERAL AREA WHERE THE RPTR HAD HIS PROB. THE RPTR BELIEVES THAT IT MIGHT BE CAUSED BY INTERFERENCE BTWN THE ANTENNA FOR THE TELEPHONE THAT IS INSTALLED IN SOME OF THE ACFT. THE ZOA SUPVR TOLD THE RPTR THAT THERE IS A MEMO FROM ZOA TO THE ACR REGARDING THIS PROB. SEVERAL PEOPLE AT SEVERAL HIGHER LEVELS; BOTH WITH THE ACR AND THE FAA; ARE AWARE OF THIS PROB AND MAY BE WORKING ON IT. THE RPTR HAS ASKED FOR THE ATC TAPES TO BE PULLED AND REVIEWED FOR THIS INCIDENT; BUT HAS NOT YET HEARD THE TAPES. THE RPTR STARTED EVASIVE ACTION BEFORE ATC CAME THROUGH TO HIM. ARTCC HAD CALLED 3 TIMES WITH NO RESPONSE AND HAD DECIDED THAT THE RPTR'S ACFT WAS 'NORDO' AND WAS TREATING IT SO.