Kioko Mbuvi, I bought my phone from the UK (Orange) and recently I upgraded to 4.2.1 and hacktivated (unofficial activation without the original provider SIM) because I did not have the Orange UK SIM. Now in iOS 4.2.1, Apple has added a feature that constantly check for a valid push update notification (this service is used to send updates to a phone even when the App is not open, like Messenger, Skype, Facebook and has to link up with Apple server do to this). Now since I hacktivated my phone, the phone continuousness scans for these certificates in vain, using up whatever link is available be it WiFi, EDGE or 3G and ends up draining my battery in a matter of hours. Now I need this sim so that I can re-install iOS 4.2.1, activate it officially (and hence get the push certificates), jailbreak and then unlock. I was so happy, I shouldn't have upgraded but curiosity was just killing me. Anyway, iOS 4.2.1 is faster and especially if you are using iPhone 3G, you should definitely upgrade (remember to disable multitasking). And that is how this does happen. NB: if you are in a similar precarious situation like mine with the iPhone battery, this could be culprit even in iOS 4.01 and 4.1.