For a long time, equipment vendors have been nagging network managers to put voice on the LAN, but fixed-line operators have not been keen. Now, though, they're very keen - because they need to fight off mobile operators making lots of money from office staff who use mobile phones when they are inside, as well as outside, office buildings.

So the fixed-line operators have come up with an alternative mobile solution: give users a Wi-Fi phone that can reach the fixed network using VoIP over in-building wireless LANs, so they get a phone service wherever they are in the building. The customer saves money, the fixed-line operator gets revenue, and the mobile rivals lose, right?

Not necessarily. The problem here is Wi-Fi-only phones, which are big clunky battery-hogs, and worse, they don't connect to mobile GSM networks.

So, enter converged phones. Put Wi-Fi in a cellphone, and it can dial over the corporate wireless LAN or the mobile cellular network, depending on which it can latch onto. Nokia's future enterprise phones will all have Wi-Fi, and there will be other devices from Motorola and Sony Ericsson.

But it's not that simple. Nokia and other handset makers are not going to stray too far from the desires of their biggest customers - the mobile operators. They are simply not in a big hurry to demonstrate how well their phones link to Wi-Fi-enabled IP PBXs.

With mobile and fixed operators fighting to unwire your desktop phone, you can count on two things: a lot of confusing marketing twaddle about fixed-mobile convergence; and eventually, some good deals.