You can turn off cellular data on an Android device to avoid hitting your data cap when you're not using Wi-Fi.

Jeff Carlson writes about mobile technology for CNET. He is also the author of dozens of how-to books covering a wide spectrum ranging from Apple devices and cameras to photo editing software and ...

You can turn off data on an iPhone all at once, for specific apps, or by turning on Airplane Mode through the Control Center. Here's how to do each.