Hello..

I am faced with the exact same problem. My phone recieves calls when it feels like. I dont even get a notification that I missed a call.

I did 30 calls back to back to my galaxy S3 from a friends phone and 12 of them vanished into some other dimension - no notification on my phone that I missed those 12 calls. Every now and then, I get the message that I am not accepting any phone calls.

Also I have noticed that when I am dialling out of my galaxy S3, it beeps and cuts off.

I started noticing these issues after upgrading to JB 4.1.1

Have spoken to ATT reps several times.Changed SIM cards. Spoke to device warranty guys and got myself a new phone AND still these issues persists.

I am fed up, and trapped for another 1.5 years under ATT with an extremely unreliable phone. If any one else has these issues, please bring it up to ATT's attention.