Turn off iMessage?

I recently went abroad and switched off data roaming to save money. On my return to the UK, I found I had missed several messages because they were sent as an iMessage rather than SMS. I’ve asked, when I’m abroad in the future, that messages are sent as a standard text. The problem is, on my iPhone at least, there doesn’t seem to be a way to choose. Is there a way for either the sender or receiver to turn off iMessage? Peter Neill Yes. Tap Settings > Messages and turn ‘iMessage’ off. Or, just tap and hold the blue bubble for each message and tap ‘Send as SMS’, or enable ‘Send as SMS when iMessage is unavailable’ in Settings > Messages.