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 ...

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 ...

The subscriber identity module -- SIM -- contains the information used to connect to your wireless carrier's network from your iPhone 4. If you are planning to resell your company's iPhones, you ...

Joe's first real experience with tech came at the tender age of six when he started playing Final Fantasy IV (II on the SNES) on the family's living room console. As a teenager, he cobbled together ...