who says they have to lock it down? their spreadsheets usually. When they give you a phone for free, they have to make sure that you will return the favour: you'll have to pay the price of the phone itself plus the price of the actual voice/data service over the next 24 or 36 months. depending on the calculations and the kind of contract you have, monthly fees may not be enough to cover all of this. telcos need to make sure you actually use their services for voice calls and data; they need to prevent you from using another sim card with the phone they gave you for free. that's why they lock it. (it's obvious though, isn't it? i mean... they do lock phones. they wouldn't if it wasn't necessary.) so i get all phones that are locked for € 0,-: iphone, various androids, C7... but the N900 (when it was still available on contract, it isn't any more) was € 250,-. why? because the phone couldn't guarantee i wouldn't switch to a cheaper sim-card afterwards, paying only my monthly fees but generating profit for another carrier with each phone call. and the monthly fees alone aren't enough to give away a €500 phone for free. so that's why it needs to have sim-lock capabilities to be attractive to carriers. they need that to include it into their pricing schemes. otherwise, there wouldn't be sim-locks in the first place, right?