Originally Posted by
Foady
iPhone also seems to not like having an active EDGE session (dowloading, etc) and receiving a call at the same time.
http://docs.info.apple.com/article.html?artnum=305711
Note: While iPhone is actively transferring data over EDGE—downloading a webpage, for example—you may not be able to receive calls. Incoming calls may go to voicemail.
As
typical mentioned in the post after the one quoted above, it may be a network issue. I have had the exact same "problem" with all my phones while doing data - voice service either kills the data transmission or the call goes to VM. If by design, Apple is rejecting the call to preserve the data session, that at least ensures consistency in how the device will handle that situation. ^