Every phone you can buy on contract includes a SIM deal with a certain amount of internet and data etc.. but I already have a SIM-only contract, why can't I pay for a phone on its own every month without a SIM, rather than dropping £600 straight up to get a phone?

Welcome to DS!

Answer: no. What you want to do it buy a phone on credit, which is possible, but a different thing entirely.

You can buy an iPhone over 20 months direct from Apple without paying any interest.

http://www.moneysavingexpert.com/new...rest-free-deal

Yes, you can.

Well, at least on GiffGaff anyway. You don't need to keep a goodybag active for the duration of the loan agreement if you don't want to.

I think Argos offer finance as well.

Probably for around 25-30% APR. I swear some retailers don't know what interest rates are at the moment (or they do, but think customers don't).

Amazon was doing interest free credit over 6 months for purchases during Black Friday week/month (!) but you can always just buy on a credit card and pay it off quickly (never just minimum payment) and then you get a nice SIM-free, unlocked, probably unbranded, phone that you can do what you like with - which you may not if you buy from a network, or possibly even some high-street stores if it's a branded model.