really? I thought most phones on GSM/GPRS/EDGE data connections by default, allow the call to come through - pausing your data connection until the call is a) unanswered and auto goes to voicemail or b) user deny's the call, again sending to voicemail, or c) user accepts the call, finishes, and data traffic continues.
*Ericsson T-39/T-18z, SE W810, z500/520/600, Nokia 6620/6600, N73 all did this by default. I see no reason why an EDGE/3G device would not.