Voice over Internet (VoIP) provider Vonage started selling mobile phones that run over Wireless Fidelity (WiFi) networks instead of the traditional cellular networks. These wireless phones are expected to work as any normal VoIP phone would, but with the mobility similar to cellular phones. However, by coursing voice calls directly through the Internet rather than the cellular network, users can expect to save on long distance, and even international, call costs.

According to Vonage, existing subscribers who wish to avail the WiFi-enabled handsets will not be charged extra fees on top of the existing calling plans. Instead, they can enjoy the same inexpensive VoIP rates with the convenience of being able to place and receive calls from anywhere with a WiFi signal. And wherever they may be, they still have the same telephone number, and will be charged the same calling rates as if they were using their wired VoIP phone equivalents.

For now, however, the advantage ends with the system being inexpensive. Even in very urban areas, WiFi coverage is still not comparable to wide-reaching cellular coverage. Strong and reliable availability of a WiFi signal is still limited to the range of your home or office wireless network, or within or in the vicinity of residences with open wireless access points, airport lounges, malls, libraries, or coffee shops.

Limited as coverage can be, the issue may not be as important to telecommuting road warriors. Imagine being able to bring along your mobile office anywhere with an open or accessible WiFi signal—and this includes your WiFi-enabled laptop computer and WiFi-enabled wireless phone. It will just be as if you were at the office—same telephone number and all—only this time, you’re at Starbucks sipping cappuccino.

What I’d like to see are multi-band mobile phones that can connect to both traditional cellular AND WiFi networks. These should easily be able to automatically switch across the strongest and most reliable signal that offers the cheapest calling rates.