Adding "T" Records to Domain Names (Idea That Came to Me in a Dream)

I was dreaming about the DNS system and how awesome it is. In my dream I realized that my cell phone had a somewhat similar system to DNS built in – when I browse to a contact and select someone to call, the phone automatically resolves the name to a phone number.

Then the idea came to me:

What if I could add a “T” (telephone) record to any of my existing domain names? So if someone tries to call kirkouimet.com, it resolves to my personal cell phone number? The business implications are really cool IMO: what if I could just call pizzahut.com? If they were smart they would have their system geolocate me, find the nearest Pizza Hut, and route the call there.

  1. How hard would it be to extend the DNS functionality to include this?
  2. Is the idea good enough to pursue beyond just thinking about it?

Solution 1:

This is what srv records are for.

Solution 2:

At the domain level this is already perfectly possible - just put ENUM style NAPTR (or alternately SRV) records in your zone file.

The reason to use NAPTR over SRV is that SRV is only defined for a limited set of communications services. NAPTR records on the other hand can be used to rewrite any domain name into a URI. If the result URI is in sip: format then you use the SRV records (for _sip._udp.example.com) to find example.com's SIP gateway.

What hasn't yet been defined at IETF (although it has been talked about) is how you extend this to have different NAPTR records for each individual user at the specified domain (i.e. localpart@example.com).

You could just have localpart.example.com in the DNS, but there are concerns about how that could be managed, and also potential conflicts with real subdomains that you might want to have. i.e., what do you do if site convention is that localpart is your initials but your initials are 'www'?

This could be solved relatively easy by using localpart._name.example.com but I know from discussion I've had with one of the IETF DNSOP chairs that there's some resistance to the tendencies for DNS to be used as a generic distributed database and for the increasing use of underscore-prefix labels.

Solution 3:

This is already being done for VoIP see for instance http://www.nominet.org.uk/enum/

Solution 4:

The opposite of your idea already exists:

  • Telephone number mapping
  • RFC3761