OK, it's still just an "interim injunction" and I haven't seen the full details yet, but it looks like the wVoIP industry just scored first blood against the mobile incumbents with regard to interconnect.
I don't have time to go through all the ins & outs of this yet, but on first glance it looks like another step towards 3rd-party VoIP on mobile being given a chance to compete. Obviously there are arguments and counter-arguments on both sides, but from my point of view the fact that T-Mobile blocked access to numbers that their subscribers could reasonably expect to reach was a step too far. While I certainly appreciate the desire of operators not to subsidise WLAN-capable handsets & then see that subsidy used against them, the notion that they can just arbitrarily block outbound calls to number ranges they don't like is ridiculous.
And they made it worse by announcing to their users "You have dialled an incorrect number. Please check it & try again" - despite the inbound call coming from that very same number. If the recorded message had been honest and said "Sorry, you've tried calling a number from an operator we're still in negotiations/dispute with, please call from a non-T-Mobile phone" I would have cut them some slack.
On the other hand, if you want a well-argued contrarian viewpoint, Keith over at Telebusillis had this to say the other day