phone with split personality! (Different number after port on texts)

The issue here isn't due to iD Mobile but down to the handset you're using. It's an issue caused by Apple handsets.When you port your number in, Apple handsets don't seem to automatically update the number. This causes one of few issues which can be as follows:

• Not being able to send out texts on iMessage
• Messages saying "not delivered" but actually being delivered
• Wrong number showing on texts

There could potentially be other issues.
The fix however, should be very easy.

As you'll see in this topic: https://community.idmobile.co.uk/ios-27/number-has-been-ported-but-can-t-imessage-30268
You'll need to update the number in iMessage:
1) Try turning off iMessage (Settings > Messages)
2) then restart your phone (by pressing and holding the on/off button)
3) tap Settings > Phone > My Number and confirm that it is correct.
4) If it is not correct, please enter the correct number)
5) then turn iMessage back to On (Settings > Messages) 6) go to Settings > Messages > Send & Receive and see if the correct number is displayed under “Start new conversations from:”.
We're expecting this to resolve the issue so I'll mark the topic as resolved preemptively however, if this does not resolve the issue, just let us know here and I'll un-mark this for you and investigate.
Mohammed