i really need to know this

[uiuiy]

These days, most mobile phones come "locked" to a particular network - so for example if you bought a phone from Vodafone and later wanted to use an Orange sim card in it, it wouldn't work.

This can be annoying for several reasons. What if you have more than one mobile phone account with different networks but don't want to carry around two mobile phones? What if a friend's battery dies and they want to check their voicemail on your phone? What if you want to switch to a pay as you go or "sim only" tariff with a different provider and keep your current phone?

The only way to get around these problems is to unlock your mobile phone. It is completely legal, you own your mobile after all! The only reasons that the networks do it is to try to make sure you don't move to another network, but all it really does is stop you using your phone as you would like to!