I agree with the folk mentioning the 2G scenario. If you are on 3 or 3.5G then I think you should be okay with receiving and making a call etc. But if you are travelling and your 3G drops to 2G in certain areas due to poor reception then that could be the problem as perhaps the fault lies within the device itself of not being able to disconnect the Edge/Gprs connection for incomming calls etc.
I hope this issue is addressed in the next PR update.

Pigro, Have you had any issues whilst connected on a 2G connection? Maybe you should put it to the test so that way we could see if it really is a fault with network or the device, that is if you have the time to do so :-)