As unifi mobile has not listed as Apple’s supported carrier yet, using these features on iPhone require a bit of manual settings.
Settings > Messages > Turn on iMessage
When you see this message, don't panic. This message means to activate iMessage, your iPhone will trigger an SMS to Apple. By doing so, you may be charged for the SMS (most probably as an IDD SMS). However, as a unifi mobile user you will not be charged for this activation fee.
Once iMessage is enabled, scroll down and tap “Send & Receive”
Select your Apple ID to use iMessage.
For FaceTime, the steps are similar.
Settings > FaceTime > Turn on FaceTime.
Select your Apple ID to use FaceTime.
Because you’re using iMessage/FaceTime with your Apple ID, things can be different when using these features.
1) You will be sending iMessage using your Apple ID
2) You can only receive iMessage if another person send it to your Apple ID
3) You will be making FaceTime call using your Apple ID
4) You can only receive FaceTime call when another person calls your Apple ID
I'm Jon, I know nothing
Thanks for the info. Im waiting so long to wait imessage activate. Hope apple fix this prob. I want use phone number on imessage hm