In essence, Truphone argue they are a mobile network, and charge the resulting rate whenever T-Mobile have to use the Truphoen netwoprk to reach a caller. T-Mobile look at Truphone, don't see any transmitters or cellular infrastructure, so believe that a lower rate (similar to that charged by a fixed line company) should apply. When they couldn't come to an agreement, T-Mobile stopped connecting their customers, Truphone protested, and now it's up to the courts.
This injunction is only temporary, and is in place so the service is not interrupted while the case is going on. in essence the courts looked at Truphone's arguments and said "well they look okay, you can obviously argue the point." It doesn;t infer right or wrong on any party.