Let’s say that you meet someone at a party named Paris Hyatt, and you want to contact that person. Great, she gives you her phone number. Ready? 742-594-6734. Woah, I can’t remember that. Can you tell me again & I’ll type it in my cell phone?
Let’s say that you then meet someone else named London Sheraton. You also want to contact this person, but she says “just go to londonsheraton.com.” Great, that’s easy to remember.
Now, londonsheraton.com maps to an IP address like 126.96.36.199, but London didn’t have to tell you that.
Similarly, Paris shouldn’t have needed to tell you 742-594-6734. She should have been able to give you a friendly phone number like parishyatt.com.
In other words, phone numbers are like IP addresses. They expose a technical detail of the old phone system (e.g. 212 used to physically tell the switches to route to New York) that we shouldn’t have to deal with. So just like the DNS system for IP addresses, we should have a “DNS” system for phone numbers. So I can literally dial londonsheraton.com.
SIP helps because you can call email@example.com, but that doesn’t apply to most phones. ENUM solves this by mapping +1-202-555-1234 to 188.8.131.52.184.108.40.206.0.2.1.e164.arpa, assuming that you set up a DNS mapping from friendlyname.com to that .arpa address. So we’re almost there…