SUCCESS!!!
After several calls to CSR I gave up and send a message to Customer Support using form on their site. When they replied back I describe my situation and they were able finally to attach my number to 9900 MEID! Then, I put my 4G SIM and it starts to auto programm, it will do it several times and never stops trying. looks like it tried to activate SIM or anything, anyway, after next attempt you should call any number and you will get Welcome to your new prepaid service! After that all features except data works. Then I removed SIM and BOOM - my Thunderbolt fully working on PP

I have 1X data but I this is not so important now, I will try to get 3G later on.
So, here's my steps to get TB to PP with your old number:
1. I used youtube tutorial to manually programm it first, like unlock, add PRL, data settings etc.
2. Activated it with temp number. I used ebay dealer for 0.99 but you can find places where you can do for free (in my case when I've tried free methods I always got some error but it turned out that was a glitch in PP activation system that day).
3. With 4G SIM on auto programm it and make test call after it successfull (in this case PRL got updated). After this point it fully worked on PP with 1X data. If you don't need to port number - you are done after this step!
4. Ported my number using 9900 via ebay dealer for 0.99. Port went successfull BUT PP didn't attach my old number to this MEID.
5. Send email to customer service with ask to attach your ported numberdo so. Wait for confirmation that they did that.
6. Put 4G SIM, and start activation process (it will go automatically).
7. After you got notifacation that activation was successfull make a call, and you will get Welcome to your new prepaid service.
8. Remove 4G SIM and enjoy your TB on PP!
Hope this will help to others!
Bookmarks