ALTDEV.

Narrative

AFTER DEP FROM PHX; WE RECEIVED A CLB CLRNC TO 8000 FT. PASSING THROUGH APPROX 7000 FT; THE CAPT AND I UNDERSTOOD A CLB CLRNC TO 15000 FT. READ BACK 'ACR A; CLRED TO ONE FIVE THOUSAND.' ATC DID NOT RESPOND. APPROX 7800 FT; ACR B CALLED ATC AND STATED 'PHX DEP; ACR B; SOMEONE JUST READ BACK OUR CLRNC TO 15000 FT.' I BEGAN TO LEVELOFF (APPROX 8500 FT) AND ASKED THE CAPT TO VERIFY OUR CLRNC. THE CAPT ATTEMPTED TO CONTACT ATC; 2 OR 3 TIMES. ON THE FINAL TRY; HE STATED 'PHX; VERIFY ACR A IS CLRED TO ONE FIVE THOUSAND.' ATC'S REPLY 'WELL; SINCE YOU'RE ALREADY ABOVE 8000 FT; CONTINUE TO 15000 FT.' WE CONTINUED; NO FURTHER DEVS. HOWEVER; COM BTWN US AND ATC WAS DIFFICULT. POSSIBLE CAUSE OF PROB: 1) ATC DISTRACTED DUE TO WORKLOAD. 2) SIMILAR SOUNDING CALL SIGNS. 3) POOR RADIO RECEPTION. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE B-757 AND B-767 FOR A MAJOR UNITED STATES ACR BOTH IN DOMESTIC AND OVERSEAS RTES. HE HAD NEVER FLOWN WITH THE CAPT BEFORE THE TRIP OF THIS INCIDENT. BECAUSE OF THE STANDARDIZATION IN HIS COMPANY; HE KNOWS WHAT TO EXPECT FROM ALL CREW MEMBERS THAT HE FLIES WITH. THERE WAS A LOT OF ACFT ON THE FREQ. HAD THE OTHER ACR NOT MENTIONED THAT THIS RPTR HAD ACKNOWLEDGED THEIR CLRNC; THE RPTR BELIEVES THAT THE CTLR WOULD NOT HAVE NOTICED. THE CTLR WAS NOT RESPONDING AS HE WAS EXPECTED TO AND MAY HAVE HAD ANOTHER FREQ OR OTHER DISTR. BOTH CREW MEMBERS AGREED TO THE CLRNC AND THE CONFUSION; 'EVERYTHING WENT WELL BTWN US.' THE CTLR DID NOT SEEM TO BE UPSET ABOUT THE CONFUSION.