Current sim will not work on a new (albeit it 2g phone)

[BarkessR]

I've got a new 2g mobile and although it came with a PAYG sim, I thought I would simply be able to put my contract sim into the phone and it would work.
But its not working at all and is not recognising the sim - saying "insert sim card" yet if I insert the new PAYG sim it immediately finds it.
The contract sim does work fine in an old apple iPhone. I just needed a less complicated phone for myself so bought a basic 2g device.
Anyone any ideas as to why this should happen. My understanding is they are all backwards compatible.
(message written for the user as user does not understand any of this)

[Chris_B]

@BarkessR  what network Sim card came with that device?  Where did you get that device from?

[Northerner]

Hi @BarkessR 

Can you manually select any network. 

Thanks 

[BarkessR]

It was a PAYG EE sim and the phone is one of those daft deals you see in the paper aimed at people who cannot use smart phones (phone user is 97)

[Chris_B]

@BarkessR  It should work then if the PAYG sim is an EE sim.  the device doesn’t know the difference between PAYG and contract sims.
Just to check you have put the sim in the correct way round?  

[BarkessR]

Yes I do have it the right way round.

[bristolian]

An EE SIM is an EE SIM - PAYG vs pay-monthly is a purely billing difference.