HOW do I do that? Everyone's talking about it, did this, did that, not working etc but I can't seem to find how actually do you make calls via UMA?!

Thanks

It all depends on your wireless carrier. You have to have a special "Home Zone Calling" plan or add-on on your plan to allow UMA calling. Most mobile networks cost around $15-$20 for unlimited local or long distance. If you do not have this plan, you are charged for minutes even if connected to a wireless network.

For Tmobile, you do not need any add-on or plan. Just need an open wifi or access to a network. After you connect, instead of GSM or EDGE, it says UMA. Then you make a call as if you were on a cell network.

You can add a network through the "Manage Connections" icon. "Set Up Wi-Fi Network"