A couple of times I've had an SP answer the phone mid-session. Most of the time that just really pisses me off, completely unprofessional, mood killer, and so on. But once it was really hot.
The once it was really hot was with an SP who had just started working. It was her first or second day working, and it was obvious in many ways--she did not have that "pro" attitude, although she had killer looks, and was pretty good in bed. She was riding on top of me when her phone rang, and she told me shhh, it's her boyfriend calling. She talked to him and told him a big lie about how she was breathing hard because she ran for the phone, she'd call him back in a bit, love you baby, etc., all the while riding me.
He PLAINLY did not know that she was working as an SP. That was kind of fun.