My iPhone 3G wouldn’t connect to my Time Capsule wi-fi. I rebooted the Time Capsule and the iPhone but it still gave an error. I then tried with my 2nd home wi-fi network (Netgear DG834GT) and the same “unable to join the network” error message popped up. In case it was an issue with channel interference or WEP password mistakes I switched channels and turned all security off temporarily. This still didn’t solve anything, my MBook Pro, Air, Apple TV, Xbox etc could still connect perfectly as did my old iPhone 2G. I backed up my iPhone and then carried out a full restore but even the virginal factory fresh restored software refused to connect. Once a friend with another 3G came round and connected without a problem I had little choice but to book an appointment at Apple’s Genius bar.
The Genius tried to connect to the stores wi-fi and it failed, he checked the phone had the latest version, did a force reboot (I’d already done several) and then simply said “I’ll go and get you a new one”.
After checking for liquid damage using an otoscope to view the liquid damage indicators in the headphone socket and bottom port he gave me a new iPhone 3G and I was on my way.
Since I use MobileMe & Exchange PUSH, when I set up the accounts quickly on store on the new iPhone my contacts were pulled down onto the iPhone in under a minute which is useful since my iPhone backup was on my home machine a few hours away.