Annoying popup message in Iphone12 mini

You're welcome. If it happens again and you are not going to use iMessage and FaceTime, see this information from another ASC User, Lawrence Finch.

Stop iMessage & FaceTime SMS to servers in UK

So, for FaceTime in Settings/FaceTime first turn it on if it is off, then tap on the Apple ID and sign out.

For iMessage, Settings/Messages, turn it on if it is off, then tap on Send & Receive, the Apple ID, and sign out.

You have to actually log out of FaceTime and iMessage; just turning them off doesn’t work (it actually makes the problem worse, as the phone continues to say “hi, I’m off the air for now."

That sounds like you have not completed activation of iMessage and FaceTime. It would appear that your phone is still trying to contact the activation server, which is located in the UK, so your carrier my charge for international SMS. Is your carrier an approved Apple Carrier? They generally do not charge for the activation SMS. Check to see if iMessage and FaceTime are turned on and activated.

You can disable iMessage & FaceTime if your carrier charge you for iMessage & FaceTime.

Settings > Messages > iMessage: OFF

Settings > FaceTime > FaceTime: OFF

Or switch to a carrier that supports iMessage/FaceTime without charges.