VoIP Cell Phones

VoIP-enabled cell phones are just entering the consumer market. In the United States, only T-Mobile's HotSpot@Home service allows customers to make cell phone calls over a VoIP network. HotSpot@Home relies on a device called a dual-mode cell phone.

Image courtesy of T-Mobile HotSpot@Home lets you make cell phone calls over your home WiFi network. Learn how this useful technology integrates seamlessly between two networks.

Dual-mode cell phones contain both a regular cellular radio and a Wi-Fi (802.11 b/g) radio. The Wi-Fi radio enables the cell phone to connect to a wireless Internet network through a wireless router. If you have a wireless Internet router in your home, or if you're sitting at a Starbucks with wireless Internet access, you can use your cell phone to make VoIP calls. Here's how it works:

1. When the cell phone is in range of a wireless Internet network, the phone automatically recognizes and connects to the network.
2. Any calls you initiate on the wireless network are routed through the Internet as VoIP calls. With HotSpot@Home, all VoIP calls are free.
3. If the phone is out of range of a wireless Internet signal, it automatically switches over to the regular cellular network and calls are charged as normal.
4. Dual-mode phones can hand off seamlessly from Wi-Fi to cellular (and vice versa) in the middle of a call as you enter and exit Wi-Fi networks.

Similar to dual-mode cell phones are Wi-Fi phones. Wi-Fi phones aren't technically cell phones because they only have a Wi-Fi radio, not a cellular radio. Wi-Fi phones look like cell phones (small, lightweight handsets), but can only make calls when connected to a wireless Internet network. That means all Wi-Fi phone calls are VoIP calls.

Wi-Fi phones are useful in large companies and offices with their own extensive wireless networks. And could prove to be the next big thing, with the expanding market for municipal Wi-Fi. [source: Dr. Dobb's Portal]. Imagine that your entire city was covered by a high-speed wireless network. That means cheap (if not free) VoIP calls wherever you go.

In England, a company called Hutchinson 3G (or simply 3) has partnered with the popular VoIP service Skype to introduce the 3 Skypephone. The Skypephone allows users to make free cell phone calls to other Skype users. The phone can also make regular cell-phone calls to non-Skype users for the normal fees. Here's how it works:

1. To make a Skype call using the 3 Skypephone, you have to be on 3's cellular network.
2. To initiate a Skype call, find a Skype user in your phone's address book and press the big "Skype" button.
3. The call first goes over 3's cellular GSM network to a fixed Internet line, which then connects the call to Skype [source: mobileSift].
4. From your 3 Skypephone, you can make free VoIP calls to other Skype users whether they have a Skypephone or not. You can talk to Skype users on their PCs or using other Skype VoIP products.

The 3 Skypephone isn't currently available in the United States.

On the next page, we'll talk about how amateur radio operators are using VoIP technology.