T-Mobile HotSpot @Home Review
HotSpot@Home uses a technology called Unlicensed Mobile Access (UMA) to allow phones to make calls over Wi-Fi networks. Combining UMA with traditional cellular telephony (GSM or CDMA) in one handset, and you have a dual-mode phone that can roam between cellular and Wi-Fi networks. When in supported, open Wi-Fi coverage, the connection uses the Internet to reach the carrier's switching systems to route the call. If no Wi-Fi networks are available, the call goes through the cellular network as normal.
When at home or the office the phone makes all calls via the Wi-Fi connection, no matter how strong cell coverage may be. If you originate a call at your house/office and then leave your house/office, the phone will automatically and seamlessly switch the call from the Wi-Fi network to the regular cellular network. And vice versa: if you originate a standard cell call while out and about, then return home, the call will automatically transfer from the cellular network back to the Wi-Fi network.
This benefits us, the users, in a few ways. When calls take place over the Wi-Fi networks, they are not counted against monthly minute allotments; users simply pay a small flat rate per month for Wi-Fi calls. Also, if the user happens to live or work in an area with poor network coverage, Wi-Fi can provide enhanced localized coverage. The technology also benefits the network operators, who can free up space on their cellular networks when calls are placed over the Wi-Fi networks. This reduces their costs as well as helps provide more bandwidth to reduce the number of times users see the dreaded "network busy" message.