Unable to make audio calls on FaceTime

Re: why can’t i make FaceTime audio call only video

Does your current cellular plan, and your Carrier support this feature in your country .

Do you have FaceTime turned on in Settings > Cellular (may incur carrier charges).

If needed: See View or change cellular data settings on iPhone.

Wondering if Apple Support's online trouble-shooting article (link below) can help:

If you can't make or receive a FaceTime call on your iPhone or iPad - Apple Support

Eg: says:

• "FaceTime and FaceTime audio calling might not be available for all countries, regions or mobile carriers.
• Call forwarding isn't available with FaceTime
• A FaceTime call can't be switched into a phone call or a FaceTime audio call.

To do this, end the current call and then start a new call.

• Make sure that there isn't a FaceTime outage."