T-Mobile HotSpot @Home base station for cellular/Wi-Fi combo phone service
Why you must have it: It's nuts to have a cell phone and burn minutes at home, where you're already paying for broadband service and probably a regular or VoIP line to boot. For several years, T-Mobile has said it would change that equation, delivering cell phones that use your broadband connection at home — without incurring minutes — and then switch to the cellular network when you're out of range. This year, T-Mobile delivered, with its HotSpot @Home service. Plus, when in range of a U.S.-based T-Mobile HotSpot (such as many Starbucks Coffee stores) anywhere else, your phone also uses Wi-Fi rather than the cell network so that you're not burning minutes in those locations, either.

If the service replaces just one fixed-line phone at home, the service cost is usually paid for by those savings. Even if you keep a landline number as a general line, you could save enough cellular minutes at home to at least make a dent in HotSpot @Home's cost. And you can have multiple phones work over the HotSpot @Home router, perhaps significantly decreasing the cellular minutes you need to buy.

Your chances of having the first one on the block: High, given T-Mobile's small market share compared to AT&T, Sprint, and Verizon Wireless.

What you should know: You'll need a compatible phone, which means you're limited to the Samsung T409, Nokia 6086, and the RIM BlackBerry Curve. You can use Wi-Fi connections outside your home network and T-Mobile HotSpots, but you could get lower voice quality due to contention with data traffic. T-Mobile's coverage can be weak out of major metro areas, and the carrier has no 3G offerings and almost nothing in the way of data services on its cellular network. As with a Wi-Fi network, the service is subject to interference, which is more noticeable on a phone call then when browsing the Web.

What you need: A T-Mobile cellular service plan, plus the additional HotSpot @Home service ($20 per month). You can also get a $50 T-Mobile router for home to give phone calls priority over data traffic and to reduce the phone's battery usage when using Wi-Fi.. However, this T-Mobile device can work in access point mode when it's attached to your existing router, rather than force you to replace what you already have in place.