If both your SMS text messages and Apple iMessages aren’t working, sounds like an issue with your iD account or SIM, ​@Sarahgiff. 

Have you tried a NETWORK RESET on the iPhone with your iD SIM. Your iOS user guide explains all the reset procedures.

This community article might help. 

Hiya, yep done multiple network resets and still not working for me! 

Okay ​@Sarahgiff, with iMessage and FaceTime TURNED OFF, can you send and receive SMS text messages? 

Yes, I can send SMS when turned off

Okay ​@Sarahgiff, with iMessage and FaceTime TURNED OFF can you receive SMS text messages? 

Hi ​@Sarahgiff, 

Please let us know how you get on with the information that ​@andewhite and we can advise further if required.

Kash

Hi, yes I can recieve and send SMS messages 

Hi, after porting my number to ID network, iMessage and FaceTime won't activate.

I ran the SMSC check using #50057672# and it returned "Unknown Error," meaning my SIM isn't correctly provisioned for SMS services.

i went to Chat gtp and it started the network provider needs to reset my SMS services, refresh my provisioning, and ensure the SMSC settings are properly applied to my account?

Okay ​@Sarahgiff, you’ve said you can send and receive SMS text messages with iMessage and FaceTime turned OFF, so the SMSC number is correct. 

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

This Apple support article might help. I suggest starting at section “Remove your phone number”, then go to “Set up your phone number”.

The Apple iMessage and FaceTime services can take up to 24-hours to be activated according to Apple. 

Hi, I tried to follow the steps to remove the number but it is not showing up and unable to activate iMessage or FaceTime so maybe the reasoning why ‘send/recieve’ is not showing up. 
I attempted the SMSC again and it is stating ‘error performing request - unknown error’ so not sure what is going on