[N5S-Matter]

Never seen that one before, with my 4s and IOS7 using AT&T as a provider same as you. In fact, no issues at all these days, unlike IOS6 which disconnected all the time. With the added number, does it dial correctly? Doesn't sound like it's the phone(s) at all.

 

[N5S-Matter]

What year make and model is your car?

/____ Look over there
\

 

[N5S-Matter]

Oh ok, I am new, didn't see that. So when you get a call, it comes up correctly on your Nav screen?

Yes, it looks normal.