By plugging in the DUALjack into any standard power outlet you can wireless add a telephone jack to your house. Split into two units, the base unit plugs an electrical outlet and has a plug for the main telephone line. In the next room you plug in the extension unit which then wirelessly receives the telephone line signal. Think of it as a wireless router, but only for your telephone line. The obvious applications are things like TiVo, satellite TV (for pay-per-view programming) and fax machines.
The DUALjack is rated to have a data throughput of up to 50kbps and communicates on the 2.4GHz part of the spectrum. This is one of those things that you could probably live without until you realize that your bedroom has no telephone outlet after you've installed the dish—now how are you supposed to watch SummerSlam?