So, I’m hearing all about this FMC malarkey. What is FMC then?
Fixed-mobile convergence.

Er, great. What’s that when it’s at home?
Fixed-mobile convergence, or FMC, is all about making calls over both your landline and your mobile network with just one phone and a single phone number, whether someone’s ringing you at home or when you’re out and about.

How does it work? Sounds like witchcraft to me.
There’s no witchcraft at all. Basically, you need a dual mode phone – one that can make VoIP calls over a broadband connection as well as over a mobile network. There are a couple knocking around – and we’ll come back to the issue of handsets in a minute. So, you’ve got your dual mode phone and your internet access point – your router, your modem – whatever.

When you’re on the move, the phone acts as a normal mobile, then once you’re in range of the bridging technology – Bluetooth or wi-fi for example – which carries the call from the phone to the access point, the call switches from the cellular network to VoIP. But once you leave the environs of your home, the phone switches the call from VoIP to mobile, without dropping the call. That’s it in a nutshell.

Right. So who’s actually doing this at the moment?
The main cheerleader for this is BT, which launched its FMC service, BT Fusion, back in the heady days of June 2005.

Wow. 2005, eh? How did that go?
Erm, the reaction’s been a bit lukewarm to be honest – just 30,000 people have signed up. While technically there’s nothing wrong with the service – the handover between the networks is fine and so on – the pricing just doesn’t seem to be floating everyone’s boat. The whole idea around VoIP for consumers is about saving some pennies, which this service doesn’t really do. After all, if you’ve got a phone that does VoIP calls, wouldn’t you be looking for a Skype-style free service?

It also has a number of other grotty quirks, such as making users pay for 0800 calls that would normally be free on an old-school landline.

Miaow. What else?
Back to those handsets. You can only get two at the moment, both from Motorola. Not a huge range, to say the least, but BT is promising it is jawing with other phone companies, including Nokia, to get some more handsets on the roster.

Is this a bit of a Sinclair C5 of a technology then?
Not at all. FMC is still in its infancy but the analysts reckon it could be a bit of a cracker when it gets going and potentially worth $28bn by 2011, chiefly due to the enterprise market. Nokia has already thrown in its lot with the FMCers, launching a couple of dual mode devices and needless to say all the networking types – such as Alcatel and Ericsson – are suitably jazzed about the whole thing.

So who else is doing this FMC stuff then, apart from BT? I could do with some variety.
Well, broadband chameleon Cable & Wireless has already set out its stall on this one and bought a licence to offer its own FMC service.

Another name in the frame is O2, which trialled an FMC service back in 2004. Customers didn’t go for it, though, and plans to go live with a service were binned. Now, however, since it bought the ISP Be this week, all the rumours have kicked off again. FMC is definitely one to watch.