He isn't the brightest apple on a tree, so he always ask me about tech stuff! He has an iPhone 3G and tried putting his sim in the i4 (iPhone 4). He told me it didn't fit, so I told him to get a new sim card. He's with AT&T by the way. Can he call AT&T and get one? Is it free? How long do you think it would take to get the sim?
The new iPhone has a SIM already in it. All your friend needs to do is activate it via iTunes with his current 3GS phone number. This will simultaneously activate the iPhone 4 and deactivate the 3GS. No need to go to AT&T or get a new SIM or anything.