A320
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Workload
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Took Evasive Action; Flight Crew FLC complied w / Automation / Advisory
Airspace Structure; Human Factors
Being in contact with LA Center at 17;000 feet we were instructed to fly direct to TIJ (Tijuana) VOR. After abeam DAMUG fix we noticed an aircraft was flying direct to us 600 feet above and descending; we were instructed to climb to FL230 but at the same time we received the traffic aural warning and asked to monitor vertical speed; by the time we saw the plane it was like 2 NM and 200 feet above and the resolution [advisory] was to descend -2;200 feet/min. We followed the resolution [advisory] and almost immediately we were out of the conflict. We informed Center and were cleared to continue the climb.The frequency was jammed; it wasn't easy for the controller to repeat the instruction immediately.
A320 Captain reported Los Angeles Center frequencies were jammed; making traffic management and awareness difficult.