Calls going directly to VM

[dkincaid]

So, I'm currently running mighty 4.12 and I've noticed lately that calls are going directly to VM sometimes without ringing my phone. I've reflashed the rom and the radio, and the problem continues. I'm trying to figure out which of the following it is:

a) Rom issue
b) radio issue
c) Sprint tower/service issues
d) hardware issue

Just wondering if anyone here has experienced this problem and what they did to resolve it.

Thanks much!

D