My T once answered her cell during session and spoke to someone briefly. It really offended me. I was angry and about to leave. She explained that it was an important call about some medical tests that she had been waiting for. A week or so later she was out for surgery, expecting to be out 4-6 weeks. It turned out she was out only a week. Anyway, I decided to see if answering her cell was something she does all the time.
She only did it one other time, but that time she told me at the beginning of the session that she was expecting an important call during my hour. When it came, she excused herself and took the call outside of the room.

I am okay with both events because she explained the unique circumstances of the first call, and let me know ahead of time that she was expecting a call the second time. So, it isn't something she does routinely and I'm okay with that. Just like she is okay with my calling sometimes between sessions, needing an extra session, my financial issues that resulted in her discounting my fee temporarily to a ridiculous amount, etc.

Maybe it would be helpful to talk to her about this?