Sometimes my phone will go into no service for some unknown reason. Even if I'm at home and the phone is right next to the network extender, It will show no service and not go into service.
I have called several times to VZ support and their recommendation is to reboot the phone. I have had them swap out the phone and I still get no service sometimes. The last time I called in, I refused to reboot as this was the 4th phone I called in with this issue and they told me they could not help me unless I rebooted the phone - they would not even swap it out until after a reboot!! You would think after 3 phones they would recognize it's a bigger issue than isolated to a specific individual phone, but of course not.
There is a faster solution to solve this without rebooting the phone - turn on and off airplane mode.
menu | settings | wireless and networks | airplane mode. I think this simply restarts the network controller piece of the phone.
Once again, I am training VZ support. I don't even know why I call anymore. They always want me to a) reboot the phone or b) replace it.