iMessage not activating on my Apple device

Please try this

Turn off and restart iMessage and FaceTime

1. Go to Settings > Apps > Messages and turn off iMessage.
2. Go to Settings > Apps > FaceTime and turn off FaceTime.
3. Restart your iPhone.
4. Turn iMessage and FaceTime back on.

Try to activate your iMessage or FaceTime account online

1. Go to apple.co/IMFT-mac.
2. Under Enable Apple Account, tap Get Started.
3. Sign into your Apple Account and follow the onscreen instructions. If you use a phone number with FaceTime and iMessage, make sure to enter that phone number.

If you can’t turn on or sign in to iMessage or FaceTime on your iPhone - Apple Support

see this link for further reference

My immesge is not working on my phone with my FaceTime

Hello~ See * WheelieNick’s* post as it may be of help to you as well. Take care.

~Katana-San~