Narrative:

We departed ZZZZ on [the] SID. Departure control began vectoring us soon after takeoff with a turn to 270. We were eventually cleared to climb to FL120. Climbing through about FL100 we were cleared to climb to FL230 and turn to 210. My first officer (first officer) repeated clearance to departure control; 'heading 210; climb 230'. No further reply from departure followed that transmission. Approaching FL130 the controller asked us to verify our altitude. First officer replied with our current altitude passing (about FL130) climbing 230. The controller immediately told us to stop our climb and cleared us to level off at FL140. We complied with the new clearance and proceeded with the departure. No reason was given for the revised clearance. I had no doubt that we had been cleared to climb to FL230 and figured that a traffic issue had required the controller to modify our altitude clearance. The next morning as I thought about it I realized that although the controller didn't dispute our read back to the climb to FL230 I may have misheard the altitude portion of the clearance. I may very well have heard our call sign and with the language issues in [foreign airports] it sounded like climb [the call sign of our aircraft] to me. If I did misunderstand the clearance it was due to a combination of factors. 1. The inherent language difficulties when flying in [foreign airspace]2. Controllers switching back and forth between [a foreign language] and english as he communicated with [local] and [international] flights.3. High inbound and outbound traffic load resulting constant radio chatter in both [a foreign language] and english.4. Confusing our call sign; air carrier X as a clearance to climb to [a similar end number]. The only variable that can really be controlled is the call sign. If we had been air carrier Y I don't think it likely that I would have misconstrued that as an altitude clearance but as air carrier X it may have been misunderstood as an altitude.

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Original NASA ASRS Text

Title: B777 Crew reported ATC called for an intermediate level off during climb out from a foreign airport which may have been attributed to misunderstanding the clearance.

Narrative: We Departed ZZZZ on [the] SID. Departure Control began vectoring us soon after takeoff with a turn to 270. We were eventually cleared to climb to FL120. Climbing through about FL100 we were cleared to climb to FL230 and turn to 210. My First Officer (FO) repeated clearance to Departure Control; 'Heading 210; climb 230'. No further reply from Departure followed that transmission. Approaching FL130 the controller asked us to verify our altitude. FO replied with our current altitude passing (about FL130) Climbing 230. The Controller immediately told us to stop our climb and cleared us to level off at FL140. We complied with the new clearance and proceeded with the Departure. No reason was given for the revised clearance. I had no doubt that we had been cleared to climb to FL230 and figured that a traffic issue had required the controller to modify our altitude clearance. The next morning as I thought about it I realized that although the controller didn't dispute our read back to the climb to FL230 I may have misheard the altitude portion of the clearance. I may very well have heard our call sign and with the language issues in [foreign airports] it sounded like Climb [the call sign of our aircraft] to me. If I did misunderstand the clearance it was due to a combination of factors. 1. The inherent language difficulties when flying in [foreign airspace]2. Controllers switching back and forth between [a foreign language] and English as he communicated with [local] and [international] flights.3. High inbound and outbound traffic load resulting constant radio chatter in both [a foreign language] and English.4. Confusing our call sign; Air Carrier X as a clearance to climb to [a similar end number]. The only variable that can really be controlled is the call sign. If we had been Air Carrier Y I don't think it likely that I would have misconstrued that as an altitude clearance but as Air Carrier X it may have been misunderstood as an altitude.

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.