VoIP is about to get more attractive for UK businesses as a new registry service is set to go live. The UK ENUM registry will mean that businesses' VoIP information will be in the public domain meaning that better use could be made of lower-cost calls.

The registry, run by UK registration agency Nominet will allow users of different VoIP systems, be they proprietary like Skype or standards-based SIP devices to talk with each other, provided that they both had an existing phone number.

Nominet won out on a tender held in 2007, run by UK Enum Consortium, to run the registry. Phil Kingsland, Nominet's director of communications said that the process would work in a similar to that of the domain names; Nominet would be Tier 1 registrar while other registrars would hold the registrations for businesses. He stressed that although the underlying technology was the same for Internet domain registrations, the two databases would be held separately with no current plans to merge. He said that there were currently three registrars in the UK but expected that to grow.

In addition, Nominet would have authority for the validation agencies, the organisations that would monitor registry applications to ensure that the people applying had the authority to apply and actually owned the number in question. Kingsland said that this was to avoid some of the disputes that bedevilled the Internet in the early years.

In addition to the cost savings of using VoIP, business users will be able offer additional features such as 'follow me' allowing callers to use a single number to call someone who is not in a fixed place throughout a day - and without paying the cost of a mobile call. Kingsland said that for the first time, VoIP users would not have to belong to the same network.

The core technology of ENUM works by translating a phone number into a domain name. This allows users to continue to use existing phone number formats , while allowing the device to route the call using a DNS lookup. Kingsland said that the ‘work' would be done by the VoIP system so that a caller looking for a particular business would be diverted over the VoIP number if that business had a registration. "The caller would have to do nothing, the VoIP software will do the searching in the same way that a conventional exchange will find the number."

Kingsland said as the system had only just gone live it was too early to talk about the size of the registry but he envisaged steady progress rather than rapid take-up.