ACR TAKES EVASIVE ACTION FROM ACFT SAME ALT.

Narrative

THE INCIDENT OCCURRED DURING 66 MI NE OF BLD VOR AT 330. WE WERE ON LAX CENTER FREQ 126.35 AND COULD HEAR CONVERSATIONS BTWN LAX AND OTHER ACFT. DUE TO TSTMS IN THE AREA; WE HAD OUR WX RADAR ON AND ALSO HAD OUR TCAS SYS ON. AT THIS POINT I SPOTTED AN ACFT ON TCAS AT 12 O'CLOCK 35-38 MI AT OUR ALT. THIS ACFT CONTINUED INBOUND AT OUR 12 O'CLOCK AND REMAINED LEVEL OUR ALT. AT 30 MI OUT IT IS COMMON OCCURRENCE TO SEE TFC AT YOUR LEVEL. THEN THEY EITHER CLB OR DSND OR TURN. THIS TARGET DID NOT. AT 20 MI OUT STILL AT 12 O'CLOCK I CALLED LAX CENTER ON 126.35 AND ASKED ABOUT THIS TARGET ACFT. MY FIRST CALL WAS BLOCKED BY ANOTHER ACFT. ON THE SECOND ATTEMPT LAX SAID I WAS ON THE WRONG FREQ AND TO GO TO 124.2. WE THEN GOT A TA OF TFC FROM TCAS. I WENT OUTSIDE AND SPOTTED THE TARGET ACFT AT 12 O'CLOCK OUR ALT. APPROX 8 MI OUT THE FO CALLED LAX ON 124.2 AND ASKED WHAT THIS TFC WAS DOING. TCAS THEN WENT RA; CLB; CLB. SINCE WE WERE IN VISUAL CONDITIONS WE STARTED A TURN 30-40 DEG TO L OF COURSE; AS SOON AS TCAS SAW THE DISTANCE OPEN UP. IT WENT TO A MONITOR VERTICAL SPD WARNING. WE LATER DETERMINED THAT THE TARGET ACFT HAD STARTED A SLOW DSCNT AT APPROX 5 MI OUT. TCAS WORKS! TARGET ACFT PASSED 500-800 FT BELOW US AND 1.8-2.5 MI ON OUR R SIDE. HAD WE NOT TURNED IT WOULD HAVE BEEN VERY CLOSE. WE ELECTED TO TURN IN ORDER TO STAY WITHIN THE CONFINES OF OUR AIRWAY RATHER THAN CLB INTO SOMEONE ELSE'S AIRSPACE. ATC ON 124.2 THEN HANDED US OVER TO SLC. LAX WAS ANXIOUS TO HAND US OFF. I BELIEVE THE INCIDENT OCCURRED DUE TO ATC AT LAX COMBINING SECTORS; AT NIGHT AND NOT HAVING THE COMBINED SECTORS ON 1 FREQ. THE CTLR ON 126.85 WAS WORRIED MORE ABOUT THE FREQ CHANGE TO 124.2 THAN THE TFC CLOSING ON MY ACFT. BOTH LAX CTLRS ON 124.2 AND 126.35 WERE MORE INTERESTED IN CYA THAN EXPLAINING WHAT HAPPENED.