Switching carriers or using a different SIM card on your iPhone doesn’t have to be complicated. If your device is SIM-locked, ...

To check if your Android phone is unlocked, try swapping in another SIM card or test your network settings. If calls work, ...

A user has an iPhone 3G from a relative in France. Has the phone, but no SIM card. Can't activate it initially because he has T-Mobile, so no valid SIM at all. I can't even use an ATT SIM (in US ...