iPhone 5S locked or not?

[thepigf@rmer]

I've been thinking about getting an iPhone 5S on contract (Tesco) for my daughter but may keep the phone for myself (O2)
I've read conflicting info stating that the phone will either lock to the first sim card inserted or they are already locked to the network out of the box.
I have also read that you can use Tesco sim cards in O2 phones but not the other way around.

Can anyone 100% confirm which is correct?

 

[metachi]

tesco mobile do 'piggyback' on o2 network. so you wont have problem using either network. Can you ask tesco how much does it cost to unlock?

if not you can use unlocking service like this one

http://www.ebay.co.uk/itm/O2-UK-Iph...?pt=UK_Phones_Software_RL&hash=item1e83b89672

I've used before without any problem.

 

[demonix]

Both are correct as an iPhone purchased directly from apple will remain unlocked, but if you get it from a network or a shop like the carphone warehouse then it will lock to the network of the first SIM card inserted into it.