Calypso Wireless has been granted a patent which appears to claim ownership of the whole concept behind roaming between Wi-Fi and wireless WAN networks such as GSM.

As zillions of device manufacturers have been demonstrating such devices for some time now, this looks to us like the latest in a series of attempts by lawyer-crazed companies to patent existing technology.

Calypso's patent, US Patent number 6,680,923, specifies "the seamless roaming of voice, video and data between Wide Area Network access points… and short-range Internet access points".

This is stuff that is routinely shown at trade shows - this week's prime example being the Nokia Communicator shown at 3GSM, which even included middleware from IBM to keep things connected at the application level when cutting across from one network to another. This reporter has personally heard Nokia discussing the ability to roam from Wi-Fi to cellular for the last five years.

There are plenty of companies already selling products to do the specific job Calypso claims to have patented, for instance Green Packet's SONaccess and Birdstep's Mobile IP technology.

So, if Calypso has a patent in the area you would think it must have some pretty interesting new technology, right? Well you would but as far as our reading of the patent takes us, you would be wrong.

The patent is written in the usual impenetrable patent-speak and spends a long time explaining that any device roaming between one or more different networks must be able to log onto all them (a leap in human imagination). Then it brings out its big idea: "The communication system and method of the present invention also incorporates auto-switching capabilities…"

That's right, Calypso has stumbled on what apparently no one had thought of before. If you are going to roam between different networks, you have to switch. Automatically.

"To fully understand how revolutionary Calypso Wireless' technology is, simply compare the 11,000Kbit/s speed of 802.11b to the data transfer capabilities of existing wireless cellular networks in the US," chirps the release, as if the company is single-handedly responsible for creating 802.11b.

Calypso is apparently not a hollow patent-exploiting company, as it does have roaming technology, called ASNAP. Whether this patent puts it "light-years" ahead of its competition, as the release claims, remains to be seen. It certainly appears to be ready to start milking the cash cow: "In the near term Calypso will start the process of contacting major mobile carriers in the industry to notify them of this patent," the release states.

This is only the latest in a series of weird patents to hit the industry, including Eolas' attempt to patent embedded content and BT's fabled attempt to patent the hyperlink.

Calypso is a West Indian song with improvised topical lyrics.