Hi ifraser, welcome to Talk3G and thank you for your contribution.

So, UMA is based on two key client-server elements; (1) the UMA servers at the mobile operator's network centre and (2) UMA-compatible devices (clients). The latter are not exclusive to BlackBerry but it appears that BB have implemented the technology in their entire range. Of course, the actual code in the handset is contained in the BB Operating System, but to all intents and purposes with a BB you are getting the whole rather than bits and pieces.

Now the key thing is, if the mobile operator doesn't implement UMA in their network then the BB device cannot make use of the technology.