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Voice over IP

Posted on 28 Jun 2005 at 12:38

Analysts at research group IDC predict that by the end of this year more than three million Americans will have dumped their landline in favour of VoIP, and it is not just the US that's seeing a switch to online calls. Feisty European start-up Skype is rolling them out worldwide. It maintains offices in Luxembourg, Tallin and London, and has served more than seven million minutes of PC-to-landline calls in less than two years. Its software client has been downloaded close to 100 million times and, with a user base that grows by 150,000 a day, it shows no sign of slowing down.

In the Far East, too, the idea has quickly caught on. Japanese telcos have seen 10 per cent of the population swap landlines for VoIP.

The market is starting to mushroom, and even BT is getting in on the act with BT Broadband Voice. For less than £5 a month, it will route your calls across a domestic ADSL connection, throwing in free nationwide calls on weekday evenings, and free calls all day at weekends.

The services open to UK subscribers fall into two camps: fixed and nomadic. The first, most common in a business environment where it routes calls across a LAN, is characterised by wiring and handsets that stay in place until someone moves desk or building. In a nomadic setup, users typically connect using kit that's specifically designed to be mobile, and they might well use the same number in several locations.

This latter option will make you easier to find and gives you the choice of working from wherever you like, but it falls victim to several flaws. Most often, you are left to your own devices when it comes to setup, and your mix of hardware and software will usually be cobbled together from a number of different suppliers with no guarantee they will work well together - if at all.

Then there is the issue of calling for fire, police or medical aid. This is something governments are taking very seriously, with the Canadian Radio-television and Telecommunications Commission this year giving fixed VoIP providers 60 days to find a way of routing calls to the 911 service. Nomadic services have up to a year to work out how they would do the same. In the UK, the official pronouncement is rather more prosaic, with Ofcom noting merely that 'a possible solution may be for service providers to require their end users to inform them of their address whenever they use the service from a different location. Possible technical solutions might involve dynamically updating the emergency database with the most up-to-date location whenever the user moves, or using the location interface that has been developed for mobile networks.'

For the time being, Vonage and some other service providers are routing emergency calls to the national emergency call-handling centre, which works in a slightly different way to regional centres and still may be unable to identify the location of incoming calls. BT, on the other hand, simply warns you on the Broadband Voice sign-up pages that emergency calls are currently out of the question.

Standard practice

VoIP services do not use physical connections: they use protocols, with Session Initiation Protocol (SIP) the most widely accepted. At heart, it is quite dumb, merely connecting the two callers on a peer-to-peer basis and making the hardware or software handsets at either end ring, dial and connect. The full range of features open to SIP users is dependent upon the hardware at either end of the call, making this an infinitely expandable protocol. At present, it supports voice and video calling, but there is no reason why an as yet undeveloped medium shouldn't use SIP to establish connections to other multimedia-savvy hardware at a future date.