The UK government is investigating whether to introduce a public database that links telephone numbers to IP addresses.
A consultation launched earlier this month asks interested parties to give their views on ENUM. The ENUM project uses an architecture based on the Domain Name System (DNS) to resolve telephone numbers to domain name addresses.
"ENUM is a system that links telephone numbers to Internet locations and identities such as email addresses, giving increased flexibility to electronic communications," said the Department of Trade and Industry as it kicked off the consultation.
If successfully implemented, ENUM will unify IP networks and PSTN telephony addressing, and should allow a number of Internet-based applications to be accessed via a telephone number.
"Essentially it's a way of referring to an Internet service through what looks to be a phone number," explained Dr Tim Chown of the Department of Electronics and Computer Science at the University of Southampton. "An ENUM number can be used to point to an email or messaging service, a Web page, or to call someone, perhaps using a SIP [session initiation protocol] telephone."
An Internet-based user could call another person's ENUM number and be given a range of alternative methods for getting in touch, such as email, texting or a voice call.
ENUM numbers will also mean that Internet-based applications such as streaming audio can be accessed from a telephone.
With ENUM, a telephone number is translated into an IP address in five steps. First any area and country codes are added, then any spaces and hyphens are removed. The digits are then reversed, dots are placed between each digit, and finally the domain 'e164.arpa' is added.
Thus, the mobile phone number (+44) 07879 999999 would be translated to 220.127.116.11.18.104.22.168.22.214.171.124.e164.arpa
The DTI is proposing that a committee should manage ENUM's introduction into the UK.
Whichever organisation is responsible for the top-level management of an ENUM system would almost certainly enjoy a monopoly. The government says it is keen to encourage open and fair competition between any companies that offer ENUM services in the future.
"One interesting issue for consumers is how they would be able to update their ENUM records, and whether they could move a number between providers. The ideal situation would be to have portable numbers, but the companies offering ENUM services may not welcome that," said Chown.
Chown also said that there are questions over whether spammers would be able to use an ENUM system to find targets for their unsolicited messages.
"What protection will there be to avoid people being bombarded by spam emails, text messages or calls?" Chown asked.