Hello,
I live in Emeryville, CA area (94608). I know that call quality is very poor and usually can't call around here.
But from some time last week, even in the area of Best Buy Emeryville, a call couldn't be made.
Although the antenna bar was steady 4+, right after 'call' button is hit, it said "Mobile Network is not available."
It has been like that until now and still is.
If I check the signal state and service state, it displays :

It's being charged. So don't bother with the charge level. Anyway, whether it's fully charged or not, it's like that.
Especially, take a look at 'Service state"
It says "Voice : Out of Service"
Again, I would like to stress that this area has bad and weak signal. But in my office or building, I could call previously.
( 2200 Powell St, Emeryville, CA 94608 )
However, now whereever I go ( like Best Buy Emeryville ), now it says "voice: out of service"
What shall I do? Is this a phone problem or network problem?
Thanks