Date: 201510
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Human factors: Training / Qualification; Situational Awareness; Confusion; Communication Breakdown; Workload
Second reporter function: Captain
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Aircraft TA; Person Air Traffic Control; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance; Flight Crew Took Evasive Action
Contributing factors: Human Factors; Procedure
Primary problem: Human Factors

Narrative: Sector XX verbally pointed out Aircraft X at FL370 eastbound; crossing 30 miles west at 310. There was no traffic for Aircraft X at this time. Aircraft had been deviating around undepicted precipitation all evening; which led to increased workload. The adjacent center flashed Aircraft Y; FL340 westbound deviating left ZZZ VOR when able; to sector YY which caused conflict alert to go off between aircraft Y and aircraft  X . At this time; aircraft X was out of FL360 descending to 310. I turned aircraft Y 30 left to get some lateral space between them and to keep aircraft Y from turning back on course. The two aircraft were more or less opposite direction; heads up. I thought I heard the sector XX controller say he was no longer talking to aircraft X because ZZ already had the handoff; so I called sector ZZ to ask if aircraft X was maintaining FL350. They said FL350 approved; and I responded saying that I wasn't talking to the aircraft and asked if they were. They said negative. I immediately got off the line; saw aircraft X leaving FL355 so I descended aircraft Y to FL320. Both aircraft started down at a good rate of descent. The sector XX controller yelled over saying that he was using altitude to separate the two aircraft. I told aircraft Y to maintain FL340; however; the aircraft showed FL335 and said they were already at FL320; apparently having expedited in the descent. I reissued another climb to maintain FL330. All this occurred while the sector XX controller was issuing an increased rate of 3000 feet per minute descent to aircraft X to get below aircraft Y. We were both unaware of the other's control actions as there was no coordination between the two of us. I think this occurred because of my inexperience and the lack of coordination between myself and the sector XX controller. Had I Plan View Displayed (PVDd) aircraft Y to sector XX as soon as I could before the two aircraft flashed and referenced the traffic; it would have been a non issue. Also; had the sector XX controller made it clear to me what was happening with aircraft X and that he was indeed working the aircraft; I would have only issued the vector to the south and not descended aircraft Y. My actions were taken on the presumption of sector XX no longer talking to the aircraft; which does not make much sense considering I had called the other center to verify control actions were being taken to separate the traffic and they said they were not talking to aircraft  X . I should have realized that sector XX had communications with aircraft X and trusted the controller's experience. Encourage land line coordination as that probably would have kept the entire situation from happening. I should have called sector XX to verify actions were being taken to separate the aircraft; but I did not because hearing the sector XX controller say/yell something confused the situation. Had one of us used a landline when the conflict alert went off; there would not have been a loss.


Second narrative: ATC instructed us to descend from FL 340 to FL 320 and turn 30 degrees left. We read back and complied with clearance. We saw the conflicting traffic ahead via TCAS but ATC instructions were not fixing the conflict. I verbally requested multiple times and repeated our previous clearance without any reply from ATC and we received the TCAS TA. We were then told to maintain FL 330; however; we were already at FL 320. We complied and informed ATC we were climbing from FL 320 to FL 330. I verified again with ATC our instructions and he replied; 'Company cleared to climb FL 340 and return direct to previous fix'. He then said sorry. My impression was that ATC miscommunicated instructions meant for someone else; but gave them to us. No further issues no instructions for us to call anyone or that we had done anything we were not instructed to do.


Synopsis: A high altitude Controller reported becoming confused about communications and control of two aircraft transitioning between adjacent Centers as one aircraft began descending into the path of another aircraft neither Center was communicating with. An inexperienced Controller was a factor.