The VigorIPPBX 2820 is an IP-PBX (iPBX) integrated with DrayTek's fully-featured Vigor 2820 ADSL Router. It offers a complete replacement to the traditional office phone system and analogue or ISDN lines. An IP-PBX uses your existing network and the Internet to provide company-wide telephony, using VoIP technology instead of regular phone lines or a traditional PBX. This can save hugely on line rental, provides vast flexibility, reduces call costs, maintenance and increases efficiency. IP Phones (such as the VigorPhone 350) can be placed anywhere in your office, or remotely around the world to provide one seamless phone network for your business. Wherever you have an Internet connection, you can have an extension on your PBX. All pure IP calls are free of charge; for calls to the conventional phone network (PSTN) you route via an ITSP 'Trunk' for low cost calls (for example DrayTEL).

For calls to and from the regular PSTN - the public telephone network, you need an ITSP (Internet Telephone Service Provider) who can provide you with a SIP Trunk, such as DrayTEL. Then, when your users need to make an external call, the iPBX routes automatically via the ITSP gateway on the Internet. The ITSP will also provide you with incoming phone numbers to receive calls. Those calls are routed into your VigorIPPBX 2820 which then passes to the appropriate telephones (extensions).