If you have a new phone or a new SIM card for your existing phone, activating the SIM is very straight forward. Make sure your phone is switched on and insert the SIM card. Once the SIM is inserted, ...

Activate your iPhone back to AT&T if the SIM card you insert after you install blackra1n onto the device doesn't work properly. Blackra1n is a third-party program that "jailbreaks" SIM-bearing iPhones ...

If you've just got your hands on a shiny new Sim card, congratulations. Switching your Sim (the chip that dictates your allowance) can unlock huge savings. Now comes the crucial step of activating it ...