I need direction on gsm radio 9900

Hello everyone

I do searched…

I have a worthy BB 9900 from tmobile and my carrier is att. I mep unlocked carrier free, ok.

Problem is that it doesn’t lock on att 3G either 4G/H+ just EDGE. I read somewhere that it’s cause of device radio/baseband that the bands/channels aren’t all enabled.

Question is, if I debrand it, I mean by what I learned here: wipe, nuke, nal?, sfi? and load new carrier OS (7.1), vendor removed, then the device will be able to use all it’s bands,?

of course if it’s software related and not a hardware limitation…

Anyhow, thanks in advance and I will apreciate if someone enlighten me and if can suggest me the route (and tools) that I will need.