Enum

Enum is a new internet address numbering protocol.

The Enum protocol will enable an existing full telephone number to be turned into a domain name, therby creating a multipurpose key that can be used over the internet to access a wide range of services and applications, such as Voice-over IP, e-mail or messaging.
As an example the Dublin phone number 017008500 would translate into 0.0.5.8.0.0.7.1.0 with the suffix e.164.arpa added on to the endto create a domain name similar to that used to access websites.

So if you're the person sending a message, you could be presented with whole lot of options as to how you send it.
And if you are the recipient, you can choose how you want people to contact you depending on where you are and what you are doing by selecting your preferred media.

Other benefits include the ability to receive calls over IP-based infrastructure, suche as VOIP, or by accessing web pages, all through the use of a single telephone number.

Enum is underway trial in Europe