Hey I saw you responded to my post about having the same issue and they started your new thread. Like my thread I see a lot of people are reading it but have not responded to you. The first thing I would suggest is contact RIM and file a complaint for the issue. they are currently working on it, but im sure the more complaints the higher of a priority it will become.
Secondly the issue seems to be with the t-mobile network and the vzw operating system that is on the storm 2. for whatever reason when the phone is unlocked t-mobile will reject phone calls from whatever tower or area the phone was first unlocked in, hence the "no circuit/channel available" error msg. Once you leave that coverage area and enter another it should work fine. Unfortunately for most people the area the phone first gets unlocked in has been the area they live. All we can is wait for a new operating system to hit the market or for RIM to actually fix the problem and give us an answer in laymens terms of why it doesnt work. I've heard some people have got it to work by changing there "mnc code" check this forum on crackberry.com the users over there have been way more talkative and helpful about the issue unlike blackberry forums users :(. Tmobile NO CIRCUIT/CHANNEL Avail *UPDATE* - BlackBerry Forums at CrackBerry.com