There's been mounting criticism in the tech blogosphere of Vodafone's move to lock new mobile phones so they can only be used on the Vodafone New Zealand mobile network.

Vodafone will charge $50 to unlock new handsets if people want to shift to another provider here or use someone other than Vodafone overseas for mobile roaming.

Check out the robust discussion on Geekzone where Vodafone has been slammed for what many see as anti-competitive behaviour.

Aardvark chips in here and asks whether the move "could this be the best thing that's ever happened to the grey market phone business".

Parallel imported phones are sold unlocked so can be used on any network. Will Vodafone's lock-in push people away from Vodafone stores?

We've already effectively got lock-in in this country when it comes to mobile. Telecom's phone's don't have SIM cards and use the CDMA technology of which there is only one network - Telecom's (though TelstraClear now re-sell the service). Vodafone has the only GSM network, but New Zealand Communications has built part of a network and even has some cell sites live.

It's no coincidence that Vodafone, after years of selling unlocked phones, is changing its policy as Telecom prepares to launch a GSM network and New Zealand Communications gets into the game as well.

It's speculated that NZC in particular will target Vodafone customers with cheap calling deals and urge them to bring their unlocked phones to the new NZC network. Telecom will be more focused on luring in converts with subsidised handsets procured through its new deal with global mobile phone distributor Brightstar.