Wi-Fi is a brand originally licensed by the Wi-Fi Alliance to describe the embedded technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications. Wi-Fi was developed to be used for mobile computing devices, such as laptops, in LANs, but is now increasingly used for more services, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions and DVD players, or digital cameras.
WiFi phones use different frequencies than cellular phones do. When you make a call on a WiFi phone, you dial the number of the person you want to call, just like you would with a cell phone. If you're calling another VoIP user, you may enter a VoIP address instead of a phone number, depending on the service provider's requirements.
Many of these phones use a specific WiFi service or network. For example, Netgear makes a WiFi phone for Skype service, and UTStarcom makes a WiFi phone for Vonage service. In order to use either of these phones, you need to have an account with that provider, just like you need a service plan from a cell phone provider to use a particular phone. Either you or your service provider will configure the phone to work within the network.
