Hi Michelle,
Good luck! I think all kids do it no matter if there are rules in place. When I am on the phone, my kids usually will leave me alone as they know the rule, but then sometimes they just annoy the heck out of me. When I am done with the conversation, I will ask them, what's the rule, they say, when mommy is on the phone, don't interrupt unless an emergency, then I ask them what they were doing, they will say whatever it is and say I won't do it again. But it does happen. I hope someone has a better response, but I know this is a conversation that the moms often have in my moms group.
C.