Is your iPhone not connecting to your network provider automatically? Perhaps, you just off an international flight and your iPhone is simply not detecting any available networks? In such cases, manual network selection may be required to access cellular services once again.
By default, network selection is completely automatic on iPhones and it works just fine most of the time. However, sometimes when you exit Airplane mode, your iPhone may show “No Service” after looking for a cellular signal. Moreover, if you’re traveling to a foreign country, you may need to first check the network providers that your carrier has partnered with for international roaming and then manually switch to that network upon arrival.