I still can’t activate my iMessage

Criteria: For activating iMessage, you need one-time SMS messaging service (If you have one, skip this) to be activated on your phone number. Depending on your carrier, you might be charged for this (for iMessage activation only) SMS.

If you have dual SIM then each time you switch plan between one number to another for iMessages this activation will be charged by your carrier. See the section:- Send Message with iMessage and SMS/MMS it is clearly said; additional charges may apple.

Contact your Carrier (Cellular Service Provider) The agency who issued the SIM to you to know whether you have a SMS plan enabled at least for One SMS

If your iPhone is used with a carrier not found in the wireless carrier articles, make sure you can send and receive international SMS.

See the pic below

4 Step Process --> Turn off and restart iMessage and FaceTime (The order / sequence is very important)

1. Go to Settings > Messages and turn off iMessage.
2. Go to Settings > FaceTime and turn off FaceTime.
3. Restart your device.
4. Turn iMessage and FaceTime back on (Watch the GIF hereunder)

You may seek help here --> If you get an error when trying to activate iMessage or ...