Its just bad manners to answer phone calls or texts during my time. Some girls have 2 phones and they switch off their client phone but leave their personal phone on just in case there is some sort of family crisis and I don't mind them checking that during a break.
One of my very regular girls had several regular punters and we sort of "knew each other existed" She pre arranged to ring one on them during a session so we could both see what it was like to have third party on the phone that didn't have a clue to what was going on the other end. That came about as I had suggested I rang a friend whilst fucking her but thought it was too risky so she suggested that as a safer option.
On the "fun with phones" theme, The one time we met at a local supermarket prior to our proper meeting, where my punting phone (covered with a condom and on vibrate only) was placed down her knickers in the appropriate spot and then we went into the supermarket separately, but I kept her in view. Hitting the redial on my phone and watching her jump occasionally was a definite turn on as we walked round the supermarket. A great session followed that adventure and I am glad I put the phone in a condom first, it would have been ruined due to moisture ingress otherwise! Wish she was still working, she was a great sport like that.