I actually wound up backing off using the static IP and applying QoS there. Turns out that this is only necessary in some routers. Instead, I found a few other settings that others have mentioned on various forums, and pulled them all together for use in my Linksys WRTU54G-TM router. Result: instant UMA connection, ability to make long phone calls -- crystal clear, no disconnects (first time at all doing this with UMA at home).
The thread and description are here:
http://www.blackberryforums.com/wifi...ml#post1445090