So, I took the plunge and upgraded my iPhone 3G to an iPhone 3GS in sparkly white with O2, and so far, so good.

I backed up and resynced the new device and everything worked as normal within an hour or so.

The only thing it appeared to lose was all my saved WiFi connections, no problem for the odd couple I use at home, work and at friends, but when it came to using either The Cloud or BT Openzone’s free WiFi, it kept asking me to register.

So, entering your phone number and wham… error message!

It turns out, that if your change or upgrade your iPhone, you’ll also need to call O2 to ask them to reset your MAC address associated to your account.

I called and within 60 minutes my WiFi should be re-enabled. Though they gave me a handy tip….

Save yourself waiting in a queue, if you are with O2, and experience the same issue I did, then simply send the word WIFI as an SMS to 2020 and your MAC address will be reset.

As a Russian meerkat would say… “Simples”