Iphones Calling Home On There Own?

Hi, this has happened to me and now my partner, where people back home in the uk have called us asking why we called them and hung up? We said we didn't, but they are insistent that it was our names that flashed up on there phones? We have checked our recent history and there is no trace of us ever making a call back home? It always happens Thai time in the afternoon which makes it the middle of the night in the uk! Not that people back home are annoyed, but when they get a call in the middle of the night they are then worried. Has this happened to anyone else? My dads say one time he could hear Thai voices for about 30 seconds before the line went dead. We are on AIS network. Our phones are on automatic lock after 30 secs so it isn't us calling by mistake, anyhow the recent calls log would have recorded it anyway.