I've had t take our make emergency calls before - she had a pager at one point, but sometimes it seemed out of the blue. One time she answered s calm thinking it was the emergency call she had expected, only to find out it was someone else. That time she apologized and explained that she was expecting a call that she needed to take.
I try not to freak out over little interruptions, though I have to admit if it takes longer than a few minutes or is not an emergency, I tend to get irritated (or if it happens all the time). I think I have had more t's be the ones who get irritated at themselves for their phone ringing into session than I do, but I'm also very laid back and don't expect much in general (self esteem thing and past history thing).
Well you get a chance to talk about it with your t? Do you even want to? (I know sometimes I get frustrated about things but don't want to talk to t about them for one reason or another)