Made in Sweden, the Intertex IX66 is a little wonder of a device with a huge amount to offer, both as a router and, uniquely, also as an SIP server. Moreover, by downloading optional add-on software, it can even be turned into a VoIP switchboard, making it a great product for small businesses looking for voice as well as data functionality.

At one level the IX66 is much like the other routers in this group test. The model we tested was connected to the network via a single 10/100Mbps Ethernet port (cable provided) with optional wireless connectivity available by plugging a suitable SD adapter into a slot in the side.

A cable is also included for ADSL attachment with another to connect to the dial-up side of the BT line. This can be used to provide dial-out facilities in the event of a power failure, added to which the IX66 can act as a PSTN gateway for both the locally attached phone and other SIP users - about which, more shortly.

A separate phone socket is provided for use with either an ordinary analogue handset or a headset. And a headset is included as part of the package along with everything else.

On the data side a firewall with port forwarding and content filtering facilities is built in as standard along with support for network address translation (NAT), UPnP and Dynamic DNS services. A VPN server upgrade is also available, but it's on the SIP side that the Intertex router really scores, elevating the IX66 onto a totally different plane from the others.

Sure, you can attach an ordinary phone or the headset to make and receive calls using a range of SIP service providers. However, with a built-in SIP server, it's also possible to host your own SIP domain with your own addresses (in the format myname/number@mydomain.com), rather than have to subscribe to a public service. Added to which the SIP server can be used by other LAN and, optionally WAN users equipped with either softphones or IP phone hardware, with support for calls made over the Internet and via the PSTN using either a commercial SIP provider and/or the local phone line.

Up to 15 SIP users can be accommodated altogether (extra licences are required for more than five) plus there's the option of downloading additional SIP Switch software (around £385 inc. VAT) to turn the router into a full-blown PBX (Private Branch eXchange). You can then set up detailed dial plans to route outbound calls to either the Internet or PSTN as required, forward incoming calls to local extension numbers, provide voice mail services and so on. These are facilities that are normally only available on custom PBX solutions costing thousands of pounds.

The only real drawback is a more complex management interface, although the Intertex Web interface isn't that difficult to master with lots of online support available from other users as well as Intertex itself. The lack of a bundled SIP service could also be seen as a drawback, but we had no trouble using the IX66 with a range of providers. Plus there's the SIP server and PBX switch option which really do make the IX66 stand out from the crowd and turn it into something of a VoIP gem.