>In simple terms, can my T-Mobile Curve (with Wifi) be used overseas
>to make >international phone calls back to the US via the Wifi
>connection, for much less >cost than a non-Wifi call?
A qualified yes. There is nothing stopping you from doing this. As long as your curve can associate with the access point and login to T-Mobile's UMA UNC it will work (the process is automatic and transparent to you). If you search the forums, you will find people doing this all the time.
If you have H@H from t-mobile for $20 a month, then all the voice and data is "free" when using UMA no matter where you are on the planet.
If you use any wireless hotspot (usa or overseas) that blocks UMA ports (ipsec) for any reason, then UMA won't work. This isn't a UMA problem. it's a hotspot problem - it's how the particular wireless hotspot is setup.The owner of the hotspot has every right to set that hotspot up any way they want. If the hotspot blocks UMA you're just SOL, you'll need to try other hotspots until you find one open to UMA.
If you are technically proficient enough, the curve contains troubleshooting tools to identify WHY a curve will not login to UMA through a peticular hotspot. This data can often be used to find a workaround.
If you're not technically proficient, then you'll need to just keep trying different hotspots until you find one that works.
>If so, HOW (again, in simple terms, please) can one do this???
>Do I have to connect to a Wifi network in the foreign country
>(e.g., at my hotel) and then call? If so, how do I do this
>(i.e., connect to Wifi and make the call)?
>Can you explain this step-by-step, or direct me to a source that can?
Yes, you need to connect to a wifi network in order to use UMA regardless of where you are in the world.
As an aside, the UMA protocol standard defines both WiFi (802.11x) and Bluetooth as physical layers for UMA, though at this time no one has implemented UMA over Bluetooth. I think we will see it in the future.
You make a UMA call the same way you make a RAN (cell) call, punch in the number and hit the send button, it's "transparent" to the enduser (you).
As far as the "step by step" in setting up UMA and making a call on the curve, that's an RTFM question (if you don't know what RTFM means you can google it
. You can download the curve's manual at blackberry.com. The faqs and howtos and forums on this site, blackberryforums.com and others also are full of the info you are looking for. Google is your friend.
Personally I think UMA is as disruptive a technology as the cell phone system itself and has a fantastic future. It has the potential to end landline use altogether. (the cellular phone system, another great technology developed at Bell Labs and first introduced by the Bell System - the *real* AT&T - in Chicago in 1978).
In this case, the term "disruptive technology" is a GOOD thing. It's an innovation that shakes up the old order.