On 31/12/2008, at 11:31 AM, Scott Howard wrote:
On Tue, Dec 30, 2008 at 1:35 PM, lenz
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
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 -
Network Engineer, Unleash
ddi: +64 3 978 1222
mob: +64 21 129 9458