Have you tried restarting the phone with your iD SIM, ​@Tim Oakley?

Have you checked the correct phone number is displayed in the Phone app, on the device with you iD SIM?

It’s now changed and it just continues to buffer on the ‘you can receive IMessages to and reply from’ this number

Okay ​@Tim Oakley, so you can now successfully send messages as an SMS text messages (green), or by using iMessage (blue)?

Hi ​@Tim Oakley 

Thanks for getting in touch. 

We are sorry to hear there has been some issues with the service. 

Can you please clarify if you are experiencing issues with SMS or iMessages?

Thanks, 

Natalie 

I cannot send iMessages. When I enable iMessages, it tells me that “an error occurred during activation “. The number I have ported over is showing but when I click on “you can send iMessages to and receive from” with this number it buffers for ages and then come up with this error message

https://support.apple.com/en-gb/108758

This Apple support article might help. 

Perhaps start with the “Remove your phone number” procedure, then proceed to “Set up your phone number”. 

Will I lose any apps or info I delete my phone number?

No, the phone number is just data used by iOS on your iPhone.  

Hi ​@Tim Oakley  glad you got all set up with this!

Thank you ​@andewhite !