Unlock code - what exactly does it do?

[westbros]

Apologies if this has been covered before, but I did a search for "unlock code" and just got endless threads on rooting, which is not the same thing.

I currently have an HTC Desire on 3 UK from the Carphone Warehouse (CPW). I chose CPW because their phones are unlocked and unbranded.

I'm now in a position where I'm looking to upgrade to a Galaxy S3 or One X, mainly because my Desire is nearly full and I cannot load any more new apps or app updates. The problem is that CPW won't entertain an upgrade on my contract until August and as things stand neither of the phones in question are available with them on 3 UK on upgrades (although bizarrely they're happy to sell them on new contracts...don't follow the logic of that...). Whether either or both will be available on upgrades in Aug is anybody;s guess, but I'm not hopeful considering the One X has been out for nearly 2 mths already and still isn't available.

On the other hand my local 3 Store WILL offer me an upgrade from now (at a fee), but it would of course be a branded and locked phone. I explained that there's a chance I might be moving abroad and that's why I would prefer unlocked and unbranded. I was told that for

 

[Hadron]

It is just a SIM unlock, nothing else. I don't know Samsung devices, but the code will not remove the branded firmware.

 

[AndroidSPCS]

Unlock code only unlocks the GSM carrier lock, typically has no other effect.

 

[mrsbelpit]

Also keep in mind when you unlock a carrier branded phone you typically have to change settings for mms and the like to work with your new carrier. That's generally easy to find via Google if it's a popular phone.

 

[westbros]

Thanks. That's what I thought.

 

[westbros]

One other question on this, if I may?

If I were to get a branded phone and then get it unlocked and move abroad and put a foreign SIM in it, when it comes to software updates would I get the updates of the foreign network or would the phone still try to download updates from 3 UK? In other words, is it the software on the phone or the network on the SIM that defines what updates you get? (Hope this makes sense...)

Thanks again.