SIM

Hi ​@BMCC 

The SIM card number starting with 254 likely indicates a provisional number allocated by iD Mobile before the number port is fully completed. When you switch to iD Mobile, your phone might initially recognize this provisional number, even after the number port is finalized. This can sometimes cause issues with calls and texts. 
The complete SIM card number is usually 19 digits long and starts with 894420. You can find the full number on your iD Mobile receipt, SIM card holder (see below pic) or in the welcome email. 

You state that it is only your data that isn’t connecting? Or is it calls and texts as well?

If it is only your data and you have now tried 2 SIMS then it may be your phone.

If you do an internet search (obviously not on your phone 😁) with regards to this problem e.g. iphone 16 pro max won't connect to mobile data, then you will see that it is a known problem and not down to the network you are connected to or anything to do with the SIM.


Here is some info with regards to data connection problem with your phone:-
https://www.idmobile.co.uk/internet
https://www.idmobile.co.uk/help-and-advice/get-your-settings

https://www.idmobile.co.uk/data
 

‘The only way to reconnect is to put the phone in airplane mode briefly’
 

VPN:

If you use a VPN, try disabling it temporarily to see if it's causing the issue. 

https://deviceguides.ee.co.uk/mobile/apple/iphone-16-pro-max-ios-18/connectivity/resetting-network-settings/

Hopefully something within the advice will help!

Good Luck x

Hi ​@BMCC 

​@Decembersangel72 has you covered with the above here, the pre-entered numbers are before the number printed on the SIM itself, or on the packaging start after those pre-entered numbers.

Tom