I get error turning on iMessage on my iPhone

Hello sgeva289,

Welcome to Apple Support Communities!

We want to help resolve this iMessage Activation error so you can send messages without any issue again.

We see you viewed the Apple Support page for Use Messages on your iPhone or iPad - Apple Support

For this particular error, we'll want to start with these steps:

"Check your device settings

1. Make sure that you’re connected to a cellular data or Wi-Fi network. 
2. If you're using an iPhone, you need SMS messaging to activate your phone number with iMessage and FaceTime. Depending on your carrier, you might be charged for this SMS.
3. Go to Settings > General > Date & Time and make sure that your time zone is set correctly."

This Apple Support page has the full details and additional steps to take: If you can’t turn on or sign in to iMessage or FaceTime - Apple Support

There is a link to contact Apple Support directly at the end of the article if needed

We hope this helps to quickly get iMessage activated again to resolve the error and issue.

Cheers!