Does FaceTime audio call convert to a cellular call (not cellular data) when WiFi drops

Hello TransparentAndOpen,

We understand wanting to manage your cellular data usage on the iPhone. You can use FaceTime over Wi-Fi or over cellular data. A FaceTime call can't be switched into a phone call or a FaceTime audio call, you would need to end the call and start a new one.

View or change cellular data settings on iPhone explains some important details to consider:

• If Cellular Data is off, all data services—including email, web browsing, and push notifications—use Wi-Fi only. 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.

• Set cellular data use for apps and services

• Go to Settings  > Cellular, then turn Cellular Data on or off for any app (such as Maps) or service (such as Wi-Fi Assist) that can use cellular data.

• If a setting is off, iPhone uses only Wi-Fi for that service.

We hope this helps.

Cheers.