I try to remember to put mine on silent. I used to have it on vibrate, but it would still be distracting. It's one of the things that really bothers me in my group, when everyone's phones go off. T hasn't said that people should keep their phones off, and for a long time it wasn't an issue, but lately, other group members are taking calls in the middle of group even when it's not an emergency. It's frustrating...
I've only ever taken a few calls during session. Once it was work, a few times I answer for my wife if she calls more than once. Once I answered a call from a creditor b/c it was something I was asking T's help in handling. Other than that, I try to keep my phone distractions to a minimum. Sometimes I show her journaling via my phone, but that is usually planned and with the topic of session.