Sorry for repeating myself, but in case you're not aware, "SIM FREE" iPhones from CPW will lock to the 1st SIM you put in.
If you're planning on switching to another provider down the line, you'll have to deal with CPW to get it unlocked (good luck with that).
CPW have everything to do with the iPhones they sell locking to the 1st SIM that's inserted, as no one else does it, it's solely a CPW thing.
Also, Three are the exception when it comes to unlocking, as their new policy will unlock locked phones from other networks, or ones locked to 3, for free.
When you stuck your 3 SIM in, the CPW "SIM Free" iPhone immediately locked to 3 (not a problem for you as you were on 3 & 3 have a great unlocking policy)
3 then unlocked it, job done.
If you had stuck an EE SIM in and locked it to EE, you would have had a hell,of a time getting EE to unlock it.
Draconian is the right word.
I've seen posts from lots of people tearing their hair out, because EE won't unlock because they are not the original owner, or making them wait 6-12 months etc etc.
Painful and unnecessary, it's almost like they devised a way to pee customers off...
There is a lot of misinformation flying around here with regard to unlocking. Azzin seems to have some very unlucky friends who haven't had good service...
The situation is as follows, CPW sim free will indeed lock to the first UK sim inserted (it has to be a UK sim, so don't buy if you are considering using or sending abroad). They have
nothing to do with unlocking, that will be done directly through the customer services of the network you locked it to.
EE policy is 6 months of use on their network, the charge to unlock
any phone on EE is £20.42. You cannot have arrears on your account when you request the unlock.
EE unlocking page is
http://ee.co.uk/help/getting-started/joining-ee/unlocking-your-phone
Three don't routinely lock, any phone that was locked (like a CPW iPhone) can be unlocked free of charge at any time.
O2 will unlock at any time normally, but usually have a restricted period for 3-5 months after a big launch for the new model (this happened for the 5 and 5s).
Vodafone will unlock after 3 months, £19.99 until the end of 12 months, free thereafter.
There are some different rules for PAYG simcards, all details are on the OFCOM site.
http://consumers.ofcom.org.uk/phone...-provider/mobile-phone-locking-and-unlocking/
Here's a few stuff about my experiences since I'm in the UK.
I arrived in 2010, signed to Voda, creepy service, quite quick web browsing but pathetic coverage.
After my contract finished with T, I went to try a 1 month SIM with Three (it was just before the 5s launch). The sh*ttiest service ever! They have unlimited internet, which you cannot tether (only 2GB), they have 4G, but it's around 15mbit/s. They use O2's signal for 2G signal, which is pathetic solution to do. (worked in telecoms),
If you arrived in 2010 I doubt you were using the O2 back up arrangement, as it had changed to Orange around 2008, by 2010 Three were starting to remove the 2G arrangement in many areas as they had sufficient native coverage due to the MBNL rollout. The 2G backup wasn't pathetic, it allowed Three customers to have voice and text in rural areas where Three hadn't yet been able to get masts installed, MBNL solved the problem (worked for a network in telecoms

).
For example
http://www.theregister.co.uk/2010/11/08/3uk_orange_roaming/
Since then, I'm on EE, love them! Their ****** policy on unlocking is terrible, I agree. You gotta wait 6months of you contract +25£ on top for ONLY IPHONES. Other phones can be unlocked for like 15£ I remember. (it's a bad joke)
Completely wrong, see my post above, all phones cost £20.42 to unlock for all EE brands, I've even added the link above for verification.