Would 2G even have the bandwidth necessary for a VOIP call? I wouldnt have thought so.. It was designed for voice, and limited quality voice at that, and you want to pass data (with the packet information and routing protocol overheads added in) over it?

Don't bash the phone; youre up against a bandwidth limitation inherent to the GSM network design, using a technology froma time when the concept of internet didnt even really exist on PCs, let alone phones..