I recently tried my 8320 out in Costa Rica with the aim of using Wifi for data and UMA as my primary method of calling back home. I encountered mixed results in Costa Rica hotspots myself...with most problems on establishing a UMA connection. From reading other posts and conducting several tests myself, this was probably due to one or more of the following problems...everyone feel free to chime in with your thoughts/experiences.
1) I wonder about the weak signals I encountered. This is based on my experience at one hotel - I could not get UMA active until I had 3 or 4 bars on the Wifi signal indicator...interestingly, Wifi signals were weak at every hotspot in Costa Rica and I had to practically stand on top of the antenna to get a strong signal...perhaps there is some regulation in CR that weakens Wifi signals in public? Has anyone else found this to be true? Interestingly enough, with weaker signals, I was able to surf the net, but not able to establish a UMA connection.
2) Perhaps the WiFi spots I encountered had lower-speed connections? One test I ran had a speed of 300k. Can anyone confirm minimum connection speed necessary to establish UMA connection?
3) Finally...there was a TMO UMA outage while I was there. My luck!?!