Here is How to turn on iMessage on your iPhone.
iMessage is super easy to start using right out of the box but you’ll need to configure a few things first.
Well, Here is How to do it;
Check your device settings
Make sure that you’re connected to a cellular data or Wi-Fi network. If you’re using an iPhone, you’ll need SMS messaging to activate your phone number with iMessage
Go to Settings > General > Date & Time and make sure that your time zone is set up correctly.
Still not activated (Turned On) after an hour?
It might take a few minutes to activate iMessage and FaceTime. If you’ve waited more than an hour, try these steps:
1. Make sure that your device has the latest version of iOS.
2. Contact your carrier to make sure that you can receive SMS messages.
3. Contact Apple Support.
Get more help
You can also use your email address with iMessage . Get help if you have trouble verifying your email address: