Martin Courtney

Skype and other types of free PC-to-PC phone services are much maligned by "serious" voice-over-IP (VoIP) vendors who make a living out of selling large-scale IP telephony systems to businesses. They argue that, having experienced the poor audio quality and performance of products like Skype, firms will be put off IP telephony altogether.

It's important to remember here that while LAN telephony systems make use of infrastructure designed to handle IP telephony data ? such as routers and switches with quality of service (QoS) support and Multiprotocol Label Switching (MPLS) to minimise latency and jitter ? Skype offers no such guarantees. That said, LAN telephony costs an arm and a leg and requires a major upgrade of your network, whereas Skype-to-Skype calls are free, and the software can be downloaded and configured in five minutes.

Despite the warnings, Skype-to-Skype calls worked surprisingly well when IT Week tested the service, though there were problems with microphone volume that varied depending on the type of headset used. This frequently meant the other party had to strain to hear me, whilst the volume of their voice almost split my eardrums.

But there were no significant delays or loss of speech and neither party had to repeat themselves. After all, intermittent clipping may be permissible between friends, but is unforgivable between commercial partners or when talking to potential customers, who will vent their frustration by taking their business elsewhere.

What was noticeable was very poor audio quality, with significant distortion always threatening to scupper the conversation on Skype-to-landline calls, and effectively rendering Skype-to-mobile phone communications pointless.

Using Skype over a domestic ADSL link shared between three computers is probably not the best way to ensure an IP conversation has the bandwidth it needs. But many vendors say no voice over IP (VoIP) service should ever need more than 90kbit/s of capacity to support sufficient audio quality and performance, so this should not have presented a problem.

Despite this, competition in the peer-to-peer IP telephony market looks set to intensify. Last week saw BT offer free local and national UK calls for three months to all new customers signing up to BT Communicator with Yahoo Messenger.

BT is also giving away free headsets to the first 10,000 customers who sign up to the service by the end of June. Let's hope they have tested these headsets to ensure that they meet the necessary audio quality requirements.

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