FLC OF AN ACR MLG RESPONDED TO CLRNC OF SIMILAR SOUNDING ACFT CALL SIGN RESULTING IN NOT FOLLOWING ASSIGNED HEADING AND TRACK.

Narrative

AFTER COMPLETING THE INITIAL TURN TO THE S ON THE DEP FROM SJC AND LEVELING AT 5000 FT MSL; WE WERE GIVEN CLRNC TO CLB TO 12000 FT. THE PNF ACKNOWLEDGED THE CLRNC AND A CLB INITIATED. ALMOST IMMEDIATELY THEREAFTER WE THOUGHT WE RECEIVED A CLRNC TO START A TURN BACK TO THE R TO CROSS THE VOR AT 12000 FT AND EXECUTE THE REMAINDER OF THE DEP. WE ACKNOWLEDGED THE CLRNC BY READING IT BACK TO THE CTLR AND EXECUTED THE CLBING TURN. HAVING NEARLY COMPLETED THE TURN; DEP CTL INFORMED US THAT WE WERE NOT GIVEN CLRNC TO TURN; BUT THAT THE CLRNC WAS ACTUALLY GIVEN TO ANOTHER ACFT WITH A SIMILAR CALL SIGN THAT HAD BEEN FLYING THE SAME DEP AFTER TAKING OFF FROM SJC 2-3 MINS AHEAD OF US. THERE WAS NO CONFLICT; NO TCASII INDICATIONS; BUT WE HAD INADVERTENTLY TURNED IN FRONT OF THE PREVIOUS ACFT AND CHANGED THE DEP SEQUENCE. WE WERE GIVEN VECTORS FOR AND EXECUTED A SERIES OF TURNS TO PLACE US BEHIND THE PRECEDING ACFT AND IN THE PROPER SEQUENCE. THE ANTICIPATION OF CLRNC TO TURN AND EXECUTE THE REMAINDER OF THE DEP; THE LACK OF ANY VISUAL CONTACT OR TCASII INDICATION OF CONFLICTING TFC; AND SIMILAR SOUNDING CALL SIGNS AND THE FACT THAT WE HAD NOT HEARD ANY RESPONSE FROM THE OTHER ACFT CONTRIBUTED TO THE MISUNDERSTOOD CLRNC. OUR READBACK WAS APPARENTLY MASKED BY THE OTHER ACFT READING BACK THE SAME CLRNC AND THE COINCIDENCE WAS NOT PICKED UP BY THE CTLR EITHER. TOTAL SIT AWARENESS AND/OR A WARNING FROM THE CTLR OF SIMILAR SOUNDING CALL SIGNS USING THE SAME DEP MAY HAVE HELPED TO ALLEVIATE THE SIT.