VFR SMT OBSERVED AND AVOIDED A WDB CLBING THROUGH HIS ALT. ARTCC RADAR CTLR DIDN'T KNOW OF TFC OR SEE IT IN CLOSE PROX.

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WE DEPARTED BDR AT XA35L VFR ENRTE TO PHL. CLBING THROUGH 4000 MSL; MADE INITIAL CALL TO NY TRACON ADVISING OF POS; ALT; DEST; TYPE; AND CRUISING ALT OF 12500 MSL. RTE OF FLT WAS DIRECT PHL. CLBING THROUGH 11000; WE WERE GIVEN A HDOF TO ZNY AND ADVISED CENTER WE WERE LEVELING 12500. APPROX 2 MINS AFTER CHKING IN; THE FO (PF) CALLED TFC 10 O'CLOCK; 5 MI AND CLOSING. I IMMEDIATELY QUESTIONED CENTER ABOUT THE OBSERVED ACFT'S ALT; AND DIRECTION OF FLT. CENTER REPLIED THAT SHE WAS UNAWARE OF ANY CONFLICTING TFC. THE TFC WAS NOW 9 O'CLOCK; 2 MI AND CLBING THROUGH OUR ALT. WE TOOK EVASIVE ACTION BY TURNING R FROM 240 DEGS TO 300 DEGS AND CLBING TO 12900 FT MSL. THIS ACTION ALLOWED OUR FLT TO PARALLEL THE CONFLICTING ACFT (A FOREIGN WDB Y). ZNY STILL HAD NO IDEA WHO THIS ACFT WAS OR WHY IT WAS IN HER AIRSPACE. AFTER THE ACFT PASSED OFF OUR 2 O'CLOCK; CLBING; WE RETURNED TO OUR ORIGINAL 240 DEG HDG AND 12500 MSL; LNDG AT PHL AT XB20 WAS UNEVENTFUL. AFTER DISCUSSION WITH NY TRACON SUPVR; WE WERE ADVISED THAT A COM BREAKDOWN HAD OCCURRED. THE WDB Y WAS ADVISED OF OUR POS AND HAD US IN SIGHT (HE WAS WORKING ZNY ON A DIFFERENT FREQ). HOWEVER; WE WERE NOT AWARE THAT HE (WDB Y) HAD A VISUAL ON US AND OUR EVASIVE ACTION COULD HAVE RESULTED IN A MIDAIR. THE NY TRACON SUPVR WAS VERY HELPFUL IN EXPLAINING HOW THE ATC MISCOM OCCURRED. ACCURATE AND TIMELY CREW COM CONTRIBUTED TO AN UNEVENTFUL RESOLUTION OF THIS SITUATION.