The Guardian


IT Departments have been centralising services and applications, using new data centres to increase efficiencies and save money. Email systems have become central hubs, for example, rather than networks of local servers. Now the same is about to happen to telephony using Voice over Internet Protocol (VoIP).

VoIP phones have been around since the 1990s, and organisations have used them to switch to one voice and data network, instead of having separate networks for phones and computers. This has led to massive deployments of IP handsets — Cisco has shipped more than 4m IP phones, with UK Bank Lloyds TSB rolling out more than 70,000 in its network.

But early VoIP solutions were often proprietary, rarely operated outside a corporate network and weren’t easily integrated with business processes and applications. Now the arrival of open standards such as SIP, the Session Initiation Protocol, have made it easier to put together a VoIP system.

SIP can handle more than just voice calls: you can manage instant messaging, presence, conferencing and event notification. Presence (knowing whether or not someone is online) could completely change the way we work with telephones. With a traditional phone, you have no idea whether the person is going to be there. Presence makes the phone part of an integrated communications tool that mixes instant messaging, email and voice. With a softphone, you can IM someone to let them know you want to talk, or even switch from voice to IM to web conferencing and back, in the middle of a conversation.

VoIP has enabled many businesses to converge their telecoms and data networks, moving voice traffic on to the WAN (wide area network). This reduces costs and allows companies to use centrally managed IP PBX (private branch exchange) systems, rather than a PBX at each site. But VoIP isn’t just for internal phone calls. Corporate VoIP networks can connect directly to the public telephone network, and you can work with a VoIP network provider to make your calls as cheap as possible.

Small businesses and home offices can set up their own VoIP networks with the new generation of SIP-based hardware. Zyxel is selling ADSL routers with two VoIP ports that work with existing phones, along with VoIP adapters that connect to any network (if you already have a router). All you need to do is subscribe to a SIP service provider, or add your own corporate SIP gateway.

Adding VoIP to a DSL router makes it easy to provide a service to home workers, or to small (one or two person) branch offices. It also makes it easier to employ staff who might normally be outside your organisation’s catchment area. For example, Wayfarers, a Guernsey-based travel agency, is using VoIP to employ qualified staff from outside the island. Home users and remote workers don’t need to worry about managing VoIP, as Zyxel’s systems can be configured centrally.

An open source alternative is Asterisk, which turns a Linux server into a business telephone exchange. Asterisk supports most common VoIP protocols, including SIP, and you can also use it to manage voice mail and your telephone directory. It will even act as a gateway between your private VoIP network and the rest of the telephone system, connecting your VoIP users to the outside world.

Traditional phone manufacturers are also looking at voice and data convergence. Polycom is launching SIP-aware IP phones that will work with common SIP servers. As well as a conference phone, there is an SIP video conferencing system.

You don’t need any hardware for SIP, which is built into Microsoft Windows XP or easily added in software. Softphones running on PCs with headsets and handsets can replace the traditional telephone handset, and a Bluetooth headset turns any laptop into an extension that can be part of an internal telephone network from anywhere in the world.

VoIP specialists Mitel equipped staff with softphones, which add collaboration and presence functions — turning an hour’s delay at an airport into productive work. Mitel’s vice president for strategic marketing, Simon Gwatkin, describes VoIP as “changing the way people communicate to match the way they work’’.

Any application can use SIP. The latest version of Microsoft’s enterprise IM client Windows Messenger (not the consumer-oriented MSN Messenger) supports SIP voice connections. While you have to use a slightly odd format to connect through SIP gateways, Windows Messenger is an interesting example of how SIP connects services that might have been seen as rivals.

Open SIP-based VoIP services behave just like email and the web, so spam, phishing and viruses are risks to be considered. High speed network connections make it relatively easy for a spammer to fill voice mail boxes with the same messages we find in email. Borderware’s SIPassure firewall appliance is a secure proxy server for SIP-based networks that can help manage your voice traffic, keeping voice mail clear, as well as protecting conversations from eavesdroppers and impersonators.