why do I keep losing bluetooth in my car

[AC Question]

I have a Casio GZ One Verizon phone. My vehicle is a 2010 Subaru Legacy. I'll be driving and I'll answer the phone and talk for whatever amount of time and then hang up. I'll get another call and I might be able to talk thou bluetooth and then I'll get another and no bluetooth. When I first start my car I never have a problem its always after that first call that I lose it. I then pull over to the side of the road turn my car off wait a few seconds restart my car and the connection is fine. But the next call or maybe the one after and no connection. This happens constantly. I sometimes think it may be the service. Never the less its very annoying.