Re: [nznog] enum

On 31/12/2008, at 11:31 AM, Scott Howard wrote:

On Tue, Dec 30, 2008 at 1:35 PM, lenz wrote: enum is a method of matching PSTN numbers to the DNS space.

That's like saying that DNS is in turn just a method for turning hostnames into IP addresses. Sure, that's what it does, but in practice it does a lot more than that - it plays a large part in allowing you to "find" a website.

Similarly ENUM allows you to "find" how to connect to a "PSTN" number (which of course might or might not actually be connected to PSTN).

If I tell you that my phone number is +1 408 500 0600, then without ENUM (or some other similar service) what option are you going to have to call me from your VOIP service? You're going to have to pay for an international call to that number, over the PSTN network and very probably via at least a 3-4 carriers. However if my VOIP provider (not necessarily me personally) had an ENUM record for that number then you could lookup the corresponding SIP address, and instead make a point-to-point connection.

How about I just tell you my "phone number" is freddie(a)beer.com, your software looks up "_sip._udp.beer.com. IN SRV", and places a call to freddie at the server returned by that record. It's an optimised, point-to-point connection, and it doesn't involve carrying over antiquities like PSTN phone numbers. We already have identifiers on the Internet - email addresses - so why we would choose to carry over cryptic strings of digits from an antiquated system and use those for one communication medium - while continuing to use email addresses as the identifiers for others - escapes me. -- Jasper Bryant-Greene Network Engineer, Unleash ddi: +64 3 978 1222 mob: +64 21 129 9458