So you have a data network and a voice network. At some point you can see the sense in combining the two -- the simplicities of management and extra functionality are worth considering.
But despite some obvious benefits of convergence, technologies such as Voice over IP (VoIP) are still in their infancy when it comes to the UK market. Japan, meanwhile, has taken to the idea with more enthusiasm, according to a recent study by researchers at Brunel University's Broadband Research Centre.
And Japan is not alone in its zealous approach to voice and data convergence. Market watchers expect a huge explosion in the global take-up of VoIP-broadband in the next few years. Juniper research predicts VoIP will be the key revenue generator for broadband service providers by 2009. In 2004, the analyst group expects a record $2.48bn (£1.38bn) to be spent on VoIP in the residential sector, rising to $6.36bn by 2009. Business spending on VoIP meanwhile is predicted to grow from a modest global $1bn this year to $9.5bn within five years.
Why that big discrepancy on VoIP over broadband between consumer and business? It turns out that US consumers are already quite happy to use broadband-based voice services, whereas UK residential customers haven't been flocking to converged solutions yet, although there are products on the market -- even from BT -- though the firm is a bit iffy about when it will introduce a business version.
Another recent study, from telecom watchers Analysys, forecast the market for broadband VoIP will be only €1.3bn in 2007, with small businesses predominating.
"The killer app for broadband is Internet access, not voice. But that doesn't mean it can't be used as a way to make calls," notes Paul Renucci, managing director of Damovo, formerly the services arm of Ericsson Enterprises. The company provides voice and data support, including converged networks, for public sector and government installations, such as the BBC and Metropolitan Police.
"We don't see voice over IP as a big driver of broadband but it will be of course an element in its deployment," adds David Atkinson, business development manager for IP Communications at Cisco UK.
But Atkinson's own company demonstrates why this is worth doing. All Cisco employees now have a soft phone on their laptop for remote access, with the same extension number as their desk phones, allowing easier home working.
One UK business already moving down the VoIP-broadband route is Zen Internet, a London- and Manchester-based Internet Service Provider (ISP). Its Rochdale-based head of Technical Development, James Blessing, explains that the firm has recently opened a second office in the town that needed to be connected as efficiently as possible. "It seemed like a good scenario for VoIP," he says.
The company was also putting together a separate VLAN (voice LAN), partitioned from the regular phone network, which would mean that no matter where a Zen staffer sits, including at home or on the road, they are still part of the same "telephone book".
The firm brought the VLAN and DSL together via investment in some new IP telephone handsets, adds Blessing.
Has it been worth it? Blessing says the pay-off can't be measured in strict hard cash terms yet but it's clear there's been an immediate return in terms of convenience and flexibility. "Working from home now means you sound pretty much like you're working in the office. We've also gained a lot more functionality with the phone system than we would have done with a fixed line system."
What about the usual VoIP bugbears -- cost and sound quality? Blessing says these aren't major hassles. "We had to buy a couple of hundred handsets, so there was a cost getting this up and running, and for future-proofing we have gone fairly top of the range in terms of actual kit. But you don't have to do that -- there are perfectly usable IP phones on the market now for around £30.
"And in terms of quality, we've built streams for 20K worth of bandwidth for voice, which is really fine if you don't get interference from the routers or are downloading a big file at the same time. If you're happy with how conversation on a mobile can sometimes sound, then you really shouldn't have that much to complain about with VoIP over ADSL," he says
But despite these benefits, Blessing warns that VoIP over broadband isn't for everyone quite yet. "As we are a fairly technical company, we didn't have that much trouble hooking all this up but I could see it could be a bit of challenge if you don't have a dedicated networking resource. It's not something a beginner could do yet, I think."
But overall Zen says that "we spent as much as possible on this because we can see that even though it might be a bit pricier than a traditional system, we've gained a lot." Eventually Zen hopes to allow its customers to connect directly into its phone system, allowing for reduced incoming calls and at some point there are plans to introduce VoIP over broadband as a product itself.
The verdict seems to be that there's no reason VoIP over broadband can't happen -- but no telco's rushing to provide it, so for the time being at least, it needs to be "home-brewed".