I had a similar issue with my iMessage not working with my phone number, and I found a solution that might help you as well. Here are the steps I took to fix the problem:
1. Go to your iPhone settings by tapping on the “Settings” app.
2. Scroll down and look for the “Messages” option. Tap on it to open the Messages settings.
3. Make sure that iMessage is turned on. You can find the iMessage toggle switch at the top of the Messages settings page. If it is already turned on, try turning it off and then back on again. This can sometimes refresh the connection.
4. After turning on iMessage, you might need to wait a moment for it to activate. It may take a few seconds or even a couple of minutes, so be patient.
5. Once iMessage is activated, scroll down in the Messages settings page and tap on the “Send & Receive” option. This will allow you to manage the phone numbers and email addresses associated with your iMessage account.
6. Look for the section titled “You can be reached by iMessage at” and make sure that your phone number is listed and checked. If it is not, tap on the “Add Another Email” option and enter your phone number. Then, check the box next to your phone number to enable it for iMessage.
7. If you see an option that says “Use your Apple ID for iMessage,” tap on it and sign in with the same Apple ID that you use on your other Apple devices such as Mac, iPad, and iPod touch. This will sync your iMessage across all your devices.
8. Once you have checked that your phone number is enabled for iMessage, try sending a test message to see if it works. If it still doesn’t work, you may need to restart your iPhone and try again.
I hope these steps help you get your iMessage working with your phone number. If you continue to experience issues, you may want to contact Apple Support for further assistance.