Why are phones locked?
In the UK, the networks operators often subsidise their phones. They do this in an attempt to attract customers to their network – consumers, particularly Pay As You Go customers, tend to be fairly network agnostic: they choose a phone that they want and then they find the network which offers the phone for the least amount of money. In order to attract these customers, networks subsidise the phones and often sell them as a “loss leader” hoping to make back the money through selling airtime. So that you can’t simply buy a subsidised phone from Network A (which loses money on the phone) and then instantly use it on Network B (which makes the profit from the airtime), the phone would be sold to you “locked” to Network A so you could only use it on that network.
