Is enum the answer to the I am not a number problem ..


I got two comments about enum to my article on I am not a number – I am a tag

Is enum the solution to the I am a tag question?

My take is – enum is a much lower level of abstraction – and hence subject to the slow uptake/control issues/standards problems. The beauty iof tags is – they are at a much more ‘user’ level of interaction. Seek thoughts?

Steve Kennedy says

ENUM goes someway towards this, people think of it as a “electronic directory” but it isn’t.

ENUM allows a user (or the owner of an electronic number) to set their own rules on how other can contact them.

It’s based on the DNS system (and if successfull will mean DNS needs a complete overhaul to cope with the added demand).

It uses what are called NAPTR (pronounced napter – i.e like napster without the s) records and these are routing/preference records for how a particular number should be routed and to where.

ENUM was specified by the ITU-T and there’s an RFC for it. It uses the DNS zone (E.164 was the ITU-T group that specified it).

It only supports numeric numbers which are stored in reverse direction, so take a random telephone number +44-20-7123-4567, this would be stored as: -

In DNS terms this is easy to parse, and fits into a hierarchical storage system (as does DNS in general).

When someone does a query for this it would start at which is managed by RIPE, they then delegate 4.4 to the UK (there is only ONE registry per country which is in UK terms will be allocated by the DTI).

The registry then holds the info for 4.4

(In the UK how the infrastructure will be run has not yet been agreed/organised, there have been some limited trials. Austria has a working ENUM infrastructure and is probably the most advanced country to date. It has been decided there will only be one registry and many registrars. A registrar can not be a registry, there are other parts beyond scope here).

So for an invidual number there’s a NAPTR entry which has URI’s telling the system how to reach that number and preferences. So it might say between 9 and 5 try the SIP address SIP:[email protected], at other times use telephone number tel:0777777777. Any type of service may be specified in the URI.

What this means is that users (or number owners) control how calls should be routed to their numbers, which potentially is disasterous for telecoms providers as they lose control (i.e. dont pass traffic over the PSTN, use IP instead), but it does go someway to the end user controlling how people contact them,Steve Kennedy

Paul Golding says ..

I think Tony’s presentation must have been aimed at old-school telco managers who don’t understand IP. Ultimately, to “find” someone in the IP-connected world, you need their IP address. This is how to “locate” someone and therefore connect. You can tag an IP address any way you like and stick those tags in a search index. If you want to use a telephone number, you can (ENUM is only one method – a “standardised” one).

However, you still need to locate the IP address somewhere on the network. In the “Next Gen” operator world (e.g. IMS, TISPAN etc.), they still intend to control that process and have fully embraced tags already, which is what SIP addresses are essentially all about.