Your IMEI has been rejected by the Vodafone UK Server as it seems not to support your IMEI number.

The Code for your phone can be obtained from Xperia World Wide Server but that code will cost you £18.99 in total.

Brand new Sony Z3 Compact on Vodafone, never had a sim card in it, could that be the issue?

Take it back to Vodafone.

And say what?

I want to use my T mobile sim in their PAYG phone 🙂

So it’s not on Vodafone then you sim card is but the phone isn’t. Yes that’s the issue

Arse!

I mean you sim card isn’t but you phone is. That little detail helps with the answer, yes the issue is your phone is locked.

To clarify, I’ve tried to get it unlocked but can’t be done. I think a PAYG phone needs a £20 payg sim in it for three months before Voda upload it to allow future unlocking.

Reckon I just need to cough up!

Yup that’s the problem.