It depends on you and your SO's relationship and also trust. Sometime is goes into a privacy matter, ask yourself do yo really want him answering your phone? Not saying that there is nothing to hide but is he helping with the bill, is he answering the phone for his security or are you letting him answer the phone to provide him security, and what has he done to get that much access of your property? Those are some question to ask your self. But the circumstances are different for everyone and everyone is different. I was in the situation before and it was more about control than me being kind and letting him answer my phone. The deal in my situation was that my boyfriend at the time wanted to have contol of who was calling my home and why the were calling but that may not be your case. What this big deal anyway, not too many people should be calling that you are not comfortable talking too while he is around. Correct?