Stupidly, I restored my phone last night - and now when I plug it into iTunes and come to activate it, it says the SIM card is unsupported. Now, I don't actually have the original SIM card as I bought it second hand, so therefore I don't know what network it's actually locked to. I'm in the UK and currently on O2.

Firmware version is 4.2.1
Baseband is 05.15.04-6.4_M3S2


any help guys?
thanks!

Good news: as you have a 3G iPhone, you can jailbreak the phone and hacktivate pretty simply. iClarified - iPhone - How to Jailbreak and Unlock Your iPhone 3G Using RedSn0w (Windows) [4.2.1]
Bad news: if you rely on carrier unlock, your restore of the phone has updated your baseband to a version that can't be unlocked by ultrasn0w

If you rely on unofficial unlock, your only option is to use the following technique Dev-Team Blog - Ultra-recycle
Please note that this comes with significant drawbacks, which you can read about in the link above and also in http://www.hackint0sh.org/f204/196391.htm

if the phone is locked to a UK carrier, it might be smarter to ask them how much an official unlock will cost.

Thanks for the quick reply Olethros, but I can't get onto the iPhone section on iTunes because it says the SIM is unsupported. Therefore I can't complete the steps you suggested.

I'm a bit of a newbie when it comes to Apple, so I have no idea where to start! :S

okay, so I got back into my iPhone - I jailbroke it and I installed Ultrasn0w so that I can unlock it.

Bad times.

The current ultrasn0w release skips my baseband and now I can't use my phone at all..
any help guys?

Originally Posted by Olethros

Bad news: if you rely on carrier unlock, your restore of the phone has updated your baseband to a version that can't be unlocked by ultrasn0w

If you rely on unofficial unlock, your only option is to use the following technique Dev-Team Blog - Ultra-recycle
Please note that this comes with significant drawbacks, which you can read about in the link above and also in http://www.hackint0sh.org/f204/196391.htm

if the phone is locked to a UK carrier, it might be smarter to ask them how much an official unlock will cost.

Originally Posted by gallifreyan

The current ultrasn0w release skips my baseband and now I can't use my phone at all..

re-read my previous reply. I have quoted the section where I gave you the answer (two answers actually!). Neither is perfect.. but we do always say that you should apply caution before restoring to the latest iOS version (for this exact reason)