Mobile phone help please

I am SO not into mobile phones so bear with me, please.

I want to get a simple mobile that just does phone calls and texts. It is to put my SIM card into for 'pay as you go' on O2. I've seen a really cheap one but it appears to be cheap because it already comes with 'pay as you go' on O2. Presumably this means I'd have to change my SIM card and mobile number?

Nope, it is cheaper because it is 'locked' to a network, in this case O2. If you already have an O2 sim card you could put your own in with no problem as it is open to the O2 network (you couldn't put another network sim in it, for example T-Mobile)

I hope this helps and makes sense

Aaaaah. You see? I have absolutely no idea! Thanks for that, very helpful!

Animal is right - you should be able to just put your sim card in it so long as it is the same network

You can buy 'unlocked' phones by themselves (which work on any network) but they generally cost more.

Thanks Azz. I've seen some sites that say you can unlock phones but I'd probably get that completely wrong.

Yeah you can unlock phones too - although I've never tried it myself.... just in case anything went wrong lol!

O2 will unlock it - for £15!!!