iPhone 4 5.0.1 Calls going straight to voicemail when using 3G data
Hi,
I've been researching this quite a bit and have seen many threads that talk about calls going to voicemail, but everything I've seen refers to Edge data vs. 3G data.
My iPhone 4 is running ios 5.0.1. Anytime I am accessing anything that uses 3G data (downloading/upgrading apps, updating news streams, watching YouTube, etc.), all incoming calls to my phone are being directed straight to voicemail. I can replicate the behavior 100% (e.g. not an 'intermittent' issue). Although the voicemail alert will eventually sound, the incoming calls do NOT show up as missed calls, so if the other party doesn't leave a voicemail, I have no idea that they've called.
Things I've already tried to do:
1) reset network settings
2) reset AT&T voicemail pin
3) visited AT&T store to receive an updated sim card and had them verify it isn't something related to my account set up (I've had the same set up since iPhone 3G, but you never know what AT&T might turn on for my 'convenience')
4) did full restore through iTunes, restoring phone from recent back up
5) full restore through iTunes setting up phone as new phone (in case there was something funky in the back up)
In every instance, it still sends the calls straight to voicemail if the phone's 3G data is in use -- and it is definitely 3G data (AT&T tower in the parking lot of my office, 80 yards from the front door).
Any ideas?
iPhone 4, iOS 5.0.1