While most people seem to manage just fine with a single SIM card in their smartphone, some -- especially travelers, who can save money by fitting a local SIM card into their handset -- love 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 ...

Once you’ve activated your iPhone with your carrier, it should continue to work on the cellular network without any problems as long as you’re within range of a tower. Nevertheless, the vagaries of ...

Do you get the error message “No SIM Card Detected” or “No SIM Card Installed” after inserting a SIM card into your phone? This problem often occurs when you ...

You don't need to lose your old SIM contacts or photos when you upgrade to an iPhone, because Apple's iOS operating system and iTunes software allow you to transfer ...