I am not exactly sure what could be causing that.

I know when I got my first blackberry I had the unknown number thing. I called Cingular and they had no answers for me. I don't know if it had to do with the fact that I got it from ebay, as a second user or what. It never effected my calls.

When it comes to the phone call making side of things, you may just want to contact your service provider. Make sure they have things working right.