One of the promoted specifications on the new Apple iPhone 4S is the "world phone" capability, but it isn't quite the world phone that many international travelers who use GSM phones are used too.

If you’re thinking of moving to a new network, and want to keep hold of the same iPhone, you may hit a snag: the device is locked to your current carrier and can’t be used with any other company.

While most people manage quite well with a single SIM card, if you want better demarcation between your work and home life, or you want to make roaming with multiple SIM cards easier, then having the ...

If you’ve bought an iPad with 4G/cellular capabilities (we discuss whether that’s a good idea in our 2015 iPad buying guide) or a new iPhone, you need to buy and install a SIM card. Here, we explain ...