Last year, T-Mobile introduced the BlackBerry Curve 8320, the first BlackBerry to support Wi-Fi with UMA technology, which lets it make calls over wireless networks. Now T-Mobile is bringing the same ability to the Curve's corporate cousin, the 8820. If you haven't heard the news, T-Mobile's HotSpot @Home service lets you make unlimited Wi-Fi calls for $10 per month. Calls you place from a Wi-Fi hot spot (including T-Mobile HotSpots) don't count against your monthly minutes total. You can also start a call in Wi-Fi mode, leave the hot spot, and then continue the free call even though the handset automatically switches back to cellular in the background. That handoff turned out to be a bit problematic in my tests, but overall, the 8820 worked exactly as advertised.