Apple has not ruled out further improvements to the iPhone that would allow it to access 3G networks, but for now the iPhone will work only with Edge (the most popular data network in the US), and GSM (most popular in Europe).

Apple vice president of worldwide iPod marketing Greg Joswiak told Macworld: “Here in the US Edge is the most widely deployed data network so that was the obvious choice.”

“Also a lot of the chip sets used for 3G are not really great on battery life at this stage so you end up with a very negative experience,” he added.

“We knew also we were creating WiFi with this product as well, and that a lot of the data usage would be through WiFi networks which are very fast,” he said.

Those who are hoping that the iPhone will offer VoIP services will be disappointed, however. “You can’t do VOIP,” confirmed Joswiak. “Edge and WiFi are the data networks and they will carry data only”.

This is one in a series of five articles featuring comment from Apple about the iPhone. Read more here:

Macworld Expo: The iPhone 'price is right'

Macworld Expo: Optimised OS X sits on 'versatile' flash

Macworld Expo: No 3rd party iPhone software

Macworld Expo: Everyone wants a piece of the iPhone

Macworld Expo: 3G future for iPhone