Use Cellular settings to turn cellular data and roaming on or off, set which apps and services use cellular data, see call time and cellular data usage, and set other cellular options.
If iPhone is connected to the Internet via the cellular data network, the , , , , or icon appears in the status bar.
LTE, 4G, and 3G service on GSM cellular networks support simultaneous voice and data communications. For all other cellular connections, you can't use Internet services while you're talking on the phone unless iPhone also has a Wi-Fi connection to the Internet. Depending on your network connection, you may not be able to receive calls while iPhone transfers data over the cellular network-when downloading a webpage, for example.
Data transfer resumes when you end the call.
If Cellular Data is off, all data services use only Wi-Fi-including email, web browsing, push notifications, and other services. If Cellular Data is on, carrier charges may apply. For example, using certain features and services that transfer data, such as Siri and Messages, could result in charges to your data plan.
Turn Cellular Data on or off. Go to Settings > Cellular. The following options may also be available:
Set whether cellular data is used for apps and services. Go to Settings > Cellular, then turn cellular data on or off for any app that can use cellular data. If a setting is off, iPhone uses only Wi-Fi for that service. The iTunes setting includes both iTunes Match and automatic downloads from the iTunes Store and the App Store.