How to disable the popup message
How to disable this message?
FaceTime and iMessage
Your network provider may charge for
SMS messages used to activate
FaceTime and iMessage.
iPhone 12, iOS 17
Question marked as
Don’t use FaceTime or iMessage. If you are seeing that message it means that your carrier does not support these features, which require regular text messages to Apple’s servers in the UK (country code +44), and which your carrier is most likely charging a fairly high per-message fee for. They will still work, but will be expensive.