My T typically has her phone on either silent or vibrate and on a table away from her. She almost never even acknowledges her phone exists while I'm in session. Once, several years ago, she did let me know that she may be receiving a call from her son and if so, she would need to respond to it. She let me know at the beginning of the session, but the call never came, so she didn't have to stop the session. Once, she had to take a call on her office phone but it was very short. Those are the only two times in 7 years that she has paid any attention to either cell or office phone.

My pdoc has an office manager that handles all his phone calls, so she never interrupts him during an appointment. I'm sure he has a cell phone, but I've never even seen it. He typically comes around in front of his desk and sits in a chair across from his patients, so he's not distracted by phone or computer.