Credit Check requirements

This information I found on the ID Mobile FAQ might help answer your question somewhat!

How do I build up a good credit rating?
A Pay monthly SIM only deal is a great way to build up your credit rating quickly and easily. It gives us a chance to get to know you, putting you in a good position to get a Pay Monthly handset contract later down the line. You can sign up for just a month at a time, so it's easy to swap to a contract once your credit rating improves. What's more, you still get great value on minutes, text messages and internet data.

Please note: a credit check is still performed for a Pay Monthly SIM only deal, but with no equipment included, lower line rentals and shorter contract lengths, while no guarantees can be given, your application would be more likely to be accepted for a Pay Monthly SIM only deal than a Pay monthly handset contract.