Apple to Apple device still sending SMS

In order for a message to be sent as an iMessage, both parties need to be signed into iMessage and have an active data connection. So, as noted in the previous responses, it's possible that the person isn't signed into iMessage. Not all Apple product owners chose to use iMessage. What is also possible is that the person doesn't have an active data connection (either WiFi or Cellular).

Can you check with this person and ensure that his/her iPhone is set up and activated for iMessages? That person may have iMessages set to OFF or not activated and that could be the reason.

The other thing that you can try is to delete the entire thread of Messages with this contact in the Messages app. Then manually type in their phone number and try and send the message. Does it now go via SMS or iMessage?

Axel F.

They might have iMessage turned off.