iMessages
Suddenly messages I use to get and send to non iPhone users have been coming back with an error Not registered with iMessages. I can’t message these numbers now and I was able to in the past. Any idea what’s happened?
iPad Air, iOS 12
Text messages that you send from your iPad to non-iOS devices will go out as SMS messages and require that you have an iPhone nearby to actually send them. Is this how you have this configured?
See if any of the following articles can help: