Apart from the odd mistake when typing in account names and passwords, we had few problems getting the VoIP enabled routers in this group test to work, either as ordinary ADSL routers or to enable us to make and receive telephone calls over the broadband link. By far the easiest, however, were those that came pre-configured for use with an online SIP service, as was the case with the Draytek Vigor 2500V and Zoom's ZoomTel X5v.

Call quality was much the same with both products and rates for calls made to the public switched network are pretty similar. That said, we preferred the Vigor 2500V as, although slightly more expensive to buy, it has a built-in Ethernet switch and a much nicer management interface. Plus you get support for things like Dynamic DNS services and UPnP which the Zoom router lacks. It can even tell you when you've e-mail waiting to be collected, making it our choice for the home user.

The Billion 7100SV is cheaper but has only one Ethernet port and no bundled SIP subscription other than Free World Dialup which can only be used to call other SIP users. The much more expensive Zyxel Prestige 2602HWL also lacks a bundled service, although it does have a built-in VPN server and two phone ports making it a good choice for the teleworker. However, the real star in terms of VoIP functionality has to be the Intertex IX66 ADSL AirSIP GW.

The Intertex router is a far from cheap solution and, again, there's no bundled SIP service, but with an SIP server built in you don't necessarily need one. Moreover, the integrated SIP server can be shared by multiple users to make and receive calls via the local phone line as well as over the Internet and via public gateways. Add the optional PBX software and you can even create your own mini switchboard. That may not tempt the average home user but it makes for a great small business solution.