As a telecommunications expert with a deep understanding of mobile technologies, I can assure you that the ability to make phone calls is not inherently tied to the availability of cellular data. Cellular data and voice services are two distinct services provided by mobile carriers. Cellular data is used for internet access on your mobile device, while voice services are the traditional means of communication over the cellular network.

When you turn off cellular data, you are essentially disabling the internet connection on your mobile device. However, this does not affect your ability to make phone calls, provided that you have a voice plan with your carrier and are within the coverage area of your network provider. Your phone will still be able to connect to the mobile network for voice calls, but it will not be able to access the internet or send/receive data-based messages like iMessages.

It's important to note that while you can make traditional phone calls without cellular data, you will not be able to use any data-dependent services such as video calling, certain messaging apps, or any online services that require an internet connection. Additionally, if you are using a device that relies solely on data for voice services, such as some VoIP phones or data-only SIMs, turning off cellular data would indeed prevent you from making any calls.

In the scenario you described, where cellular data is turned off and you are not connected to Wi-Fi, your iPhone will default to using the cellular network for voice calls and text messages (standard SMS), but not for iMessages, which require an internet connection. This means that you can still communicate with others, albeit with some limitations compared to when you have both voice and data services active.

In summary, turning off cellular data does not prevent you from making phone calls, but it does limit your ability to use internet-dependent services. It's a good option for conserving data or when you do not need internet access for a period of time.

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It's absolutely OK to turn off Cellular Data if you have a minuscule data plan or you don't need internet when you're not at home. When Cellular Data is off and you're not connected to Wi-Fi, you can only use your iPhone to make phone calls and send text messages (but not iMessages, which use data).Sep 27, 2015read more >>