ATTN: Rogers users. You can have UMA!
I just got UMA working on my unlocked Torch 9800 running on Rogers. I can confirm that automatic handover from 3G to Wifi and Wifi to 3G works also!
Here is how it's done. First you need to get to the engineering screens (which is done the same was as on the 9700). The code generator can be found here (scroll down). ESCREEN CODE GENERATOR.
Once you are into the escreens, go to "mobile network engineering screens", then "Utilities", then "Session Manager". It should show nothing.
Hit the BB key to bring up the menu and then scroll down to "UMA Options".
Hit the BB key again and select "New"
Now uncheck the default boxes and enter these settings:
http://members.shaw.ca/zerkee/ESCREEN.jpg
Back out and save it. IMPORTANT: DO NOT MESS AROUND IN THE ESCREENS AS YOU CAN BRICK YOUR PHONE.
Now you will notice that you suddenly have the option for "Wifi Preferred" in the mobile network options screen!!
http://members.shaw.ca/zerkee/NETWORK.jpg
That's it! I then had UMA with handoff!
http://members.shaw.ca/zerkee/UMA.jpg