Okay, there's voices in one's head that are normal and voices that are signs of being delusional. Similarly there is talking to one's self that is quite normal and talking to one's self that does present a problem.

Questioning to ourselves whether we are dressed okay for example, while probably a sign of anxiety, would I believe be normal. Rehearsing a conversation you need to have fits into the same category.

Having a social conversation with a voice (whether it be of someone you know or otherwise) I think warrants talking to your psychiatrist.