Narrative:

Aircraft X checked on and I informed him that I would need to climb him to 12;000 in the byi area due to the MEA. He acknowledged. When aircraft X was a few minutes away from byi; I issued a climb to 12;000. No response. I tried again to no avail. I then proceeded to have two different aircraft on a different frequency attempt to reach aircraft X to issue the climb. The other frequency is to the west side of boi instead of the one to the east. I thought it was possible that aircraft X was put on the west frequency.neither aircraft were able to reach aircraft X. I continued to try and reach aircraft X on the frequency that he should have been on and then a VFR aircraft that was in the same vicinity; again to no avail. Big sky approach also attempted and got no response. The VFR aircraft in the same vicinity as aircraft X then gave it an attempt using big sky approach's frequency and still nothing. By now; aircraft X was past byi where the MEA jumps up to 11;400 and now clipping an mia area of 11;300. I notified the controller in charge and he in turn let the next sector know. At this point; the next sector has the handoff w/ NORDO in the fourth line. Then; out of the blue aircraft X checked on and stated that a 'fellow on a different radio' called him. I issued the climb to 12;000 since there was another mia ahead above 11;000 (11;400). It appeared that he was already climbing; as the mode C showed 11;400 or 11;500 right after I issued the climb. I then coordinated with the sector that had radar control of the aircraft.I would say I should have been more aware of what frequency the aircraft was on upon check on. And I could have always issued the climb earlier and possibly been able to reach the aircraft.

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Original NASA ASRS Text

Title: A Center Controller reported attempting to climb an aircraft entering higher terrain; but lost radio contact with the aircraft.

Narrative: Aircraft X checked on and I informed him that I would need to climb him to 12;000 in the BYI area due to the MEA. He acknowledged. When aircraft X was a few minutes away from BYI; I issued a climb to 12;000. No response. I tried again to no avail. I then proceeded to have two different aircraft on a different frequency attempt to reach aircraft X to issue the climb. The other frequency is to the west side of BOI instead of the one to the East. I thought it was possible that aircraft X was put on the west frequency.Neither aircraft were able to reach aircraft X. I continued to try and reach aircraft X on the frequency that he should have been on and then a VFR aircraft that was in the same vicinity; again to no avail. Big Sky Approach also attempted and got no response. The VFR aircraft in the same vicinity as aircraft X then gave it an attempt using Big Sky Approach's frequency and still nothing. By now; aircraft X was past BYI where the MEA jumps up to 11;400 and now clipping an MIA area of 11;300. I notified the CIC and he in turn let the next sector know. At this point; the next sector has the handoff w/ NORDO in the fourth line. Then; out of the blue aircraft X checked on and stated that a 'fellow on a different radio' called him. I issued the climb to 12;000 since there was another MIA ahead above 11;000 (11;400). It appeared that he was already climbing; as the mode C showed 11;400 or 11;500 right after I issued the climb. I then coordinated with the sector that had radar control of the aircraft.I would say I should have been more aware of what frequency the aircraft was on upon check on. And I could have always issued the climb earlier and possibly been able to reach the aircraft.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.