imessage

You have to configure this. In the "You can receive iMessages to and Reply From" section, make sure that your phone number and Apple ID are selected. Link with more details Add or remove your phone number in Messages or FaceTime - Apple Support

Hello jules1220,

To isolate the issue that no issue with your Apple ID name is a good news.

It might mean that there is no block with your Apple ID.

I would recommend you to follow If you can’t turn on or sign in to iMessage or FaceTime - Apple Support

Additionally keep in mind to activate your phone number for iMessage/FaceTime, your iPhone should send/receive SMS to Apple so you must have an International SMS plan with your mobile line. And your carrier must not interfere the SMS.

I hope this helps you

Kind regards

Said