Voice over IP: now you're talking

Integrating your voice and data together using an IP network could bring considerable benefits, as long as you implement it in...

Integrating your voice and data together using an IP network could bring considerable benefits, as long as you implement it in phases, says Danny Bradbury

When public relations people and IT executives in the UK get telephone calls from this journalist (who is based in western Canada), they often ask whether it isn't expensive to be making calls so regularly from halfway across the world. Little do they know that these calls are free, because I'm talking to them via an Internet telephony service accessible from a browser.

With services such as Go2Call becoming increasingly prevalent, conventional telephony carriers are getting worried. Connecting via a PC headset over a cable modem link, I cut and paste telephone numbers from Web sites, e-mail messages or my contact database directly into the browser-based service, click on the dial button and I'm conducting an interview without even having picked up the phone.

There is a little bit of a time lag as speech travels from one point to another over the Internet when using this service, as there is with others such as Net2Phone (which unlike Go2Call imposes charges). However, such inconveniences are justified when call charges are so much cheaper, or even non-existent. When you move into virtual private network (VPN)-based calling services, where the quality of the transmission is easier to manage, such problems become minimal.

Generally, in a corporate environment where offices are spread over a wide area, voice-over-Internet-protocol (VoIP) services are implemented using a gateway product that connects to a standard exchange in the office. The gateways between the offices are linked using a high-speed leased line or managed VPN.

When employee A at the London office decides to call employee B at the California office, the call hits the local switchboard, which then passes the call to the gateway. The gateway then connects to the Californian gateway over the leased line using an IP session, and the Californian gateway patches the call through to the local exchange, giving the London caller a US dial tone. This enables them to either dial someone within their own organisation, or dial an external number from that exchange, dramatically cutting the cost of a call across the Atlantic.

The most significant benefits of a VoIP system are cost-based. If you analyse the total number of minutes that your staff spend speaking to people within a remote office, (say, a branch office or another region's headquarters), then offset that against the proposed cost of a VoIP implementation, you can quickly produce a cost benefit analysis.

Neil Wilkins, solutions marketing manager of VoIP equipment supplier Enterasys, argues that telecommunications companies will also reduce their costs to try and keep customers if the market threat becomes large enough, and certainly some incumbent telephone operators are starting to offer IP-based services to combat competition from young upstarts in the telephony market.

There are technical and political obstacles to implementing a VoIP service effectively. Nigel Williams, marketing director of VoIP services specialist Voyager Networks, explains that interdepartmental co-operation can be an issue during the planning stage. "You have to think about the fact that you're bringing together two departments in one organisation," he warns. "You need buy-in at the highest level."

In many companies, the telephony system and the IT infrastructure - including the data network - have been run by different people in different departments. Forcing them to work together takes careful team management.

Similarly, skills are an issue. Data networking experts are relatively easy to find, and telephony experts can be sourced, but hybrid experts that have sufficient technical skills in both areas are in short supply. It's vital that whoever is handling the job understands how to connect the two different infrastructures together, and this becomes increasingly important as you integrate applications into the VoIP network.

Ian Teswell, who was the in-house expert responsible for rolling out a VoIP network at the Liverpool Housing Trust, argues that the technical difficulties of implementing such solutions, and the shortage of skilled staff, should not be overlooked. He found all sorts of problems including the Cisco routers dropping voice calls after 10 minutes. However, Williams says the housing trust was an early adopter of this solution from Voyager and many of these problems have been ironed out.

Another issue to consider when implementing a VoIP network is the state of your existing infrastructure. Wilkins says, "It has to be good and robust and predictable. You can get away with a lot of things when sending data." He points out that service lapses, high latency and other network problems are more noticeable in a voice session. Consequently, you may need to review your current infrastructure, ensuring that your switches are located properly and offer a high-enough level of performance.

Generally, users start by implementing VoIP on the backbone. In doing so, they will also conduct an analysis of your existing call patterns, to ascertain the necessary capacity. Wilkins stipulates 6 kilobits per second for a voice circuit in an IP telephony link. He adds that the average company can get away with one virtual voice circuit for every 10 users on either side of the link. In heavy-use environments, however, companies should increase the provision to one voice circuit for every four users.

In many cases, network managers may want to think about varying the network provision to cope with particular business conditions - for example, decreasing the number of people per virtual voice circuit between the legal and financial departments during a corporate acquisition. This dynamic allocation will be easier if the interface between your gateway and exchange is a digital one, but might require more attention if you are connecting your gateway into an analogue port.

You will also need to think about service differentiation, to give your voice sessions priority over data communications. Wilkins prioritises traffic on the local area network (Lan) on a port-by-port basis on the switch, channelling voice traffic into certain ports that are then given a higher priority than other ports. If the traffic has to be passed over a wide area network, which would involve passing through switches, then he utilises the 801.p and 801.q traffic management standards.

Perhaps one of the biggest issues that is often overlooked by companies implementing VoIP services is billing. Many finance departments will want to keep tabs on which departments are making which calls, for internal accounting purposes. Changing not only the way that calls are made but the very nature of the calls themselves makes any existing call-tracking methods difficult to maintain.

Wilkins proposes gathering call data and then using the Lightweight Directory Access Protocol, which enables packets to be fed into a directory network service, such as the Novell Directory Service or Netscape Directory Server. Putting billing information into these services rather than a relational database enables him to use the network directory service for everything - including policy-based networking, which is so important in a VoIP environment. Policy-based networking enables administrators to set the rules that manage the service differentiation in the network, including call and data prioritisation.

Having upgraded your backbone to use VoIP services, you may think about implementing it within the Lan. Williams says companies may want to replace their branch exchange altogether with a VoIP switch. "Then the port that comes out of the wall becomes both a data and a voice port, and you plug in an IP telephone that goes into the same socket as your data point," he explains.

This may be a more adventurous approach than some companies would like. With firms still worried about the robustness of, say, Windows NT-based software, they may be loath to replace their tried-and-tested branch exchange equipment with newer equipment such as this.

On the other hand, it would help with the skills problem, because the technical staff implementing the system would at least be working with modern, open standards and not interfacing to an old, proprietary telephone exchange. Another option is to connect a computer telephony integration (CTI) switch to the exchange, in the same way that you connect the VoIP gateway for calls going out of the building. The switch would then function as an interface between the exchange and the IT infrastructure, enabling applications to be integrated with the Lan-based data/telephony infrastructure.

At this point, you can begin exploring other, more sophisticated options. Heidi Bersin, senior vice-president of corporate marketing at VoIP equipment supplier Clarent, explains that corporate voicemail is one such application. "The problem with corporate voice messaging at present is that companies require a box in each office," she says. "Using the Internet, you can give every corporation virtual local access to messages."

Other applications include unified messaging, which enables companies to channel voice, e-mail and fax messages into a single, easily-accessible mailbox. Accessing your messages from your PC using a graphical user interface would make things much more efficient because you could see which people had called you, thanks to caller line identification techniques, for example.

Clearly, VoIP has a lot to offer, but you'll want to do a lot of planning and the implementation should be iterative. Upgrade your backbone first, and enjoy the resultant cost savings, but take a look at the potential for other enhancements in the area of CTI, too - just don't try to do it all at once.

Outsourcing your VoIP infrastructure

Another option for companies that don't feel as though they have the expertise to set up a VoIP infrastructure in-house is to outsource the service to another company. Many companies are now offering third-party IP-based calling services, including DeltaThree, Inter-tel and Dialpad.

There is also a growing market for call-me buttons, which can be added to your Web site, enabling customers to initiate voice calls with your representatives while surfing the site. One company offering such services is Hearme, which offers its HearMe VoiceNetwork. The service, available for a free 30-day trial, can also be used for IP-based business conferencing. The service handles voice signals from multiple users at a time, delivering them to your desktop so that you can participate in a conference call.

The company claims that you can be up and running with the service in 15 minutes. Of course, it helps if end-users are surfing in from a high-speed corporate leased line or a home-based DSL service and not using a slower dial-up modem connection. Lynk, a division of VoIP company BOS, offers a similar service that, like HearMe's is available as a product instead of a service, if you require.

Where to find VoIP service providers

  • Go2Call

  • DeltaThree

  • Inter-tel

  • Dialpad

  • Hearme

  • Read more on Voice networking and VoIP