Page 359 - Asterisk™: The Future of Telephony

E.164
The ITU defined a numbering plan in its E.164 specification. If you’ve used a telephone
to make a call across the PSTN, you can confidently state that you are familiar with the
concept of E.164 numbering. Prior to the advent of publicly available VoIP, nobody
cared about E.164 except the telephone companies—nobody needed to.
Now that calls are hopping from PSTN to Internet to who-knows-what, some consid-
eration must be given to E.164.

ENUM
In response to this challenge, the IETF has sponsored the Telephone Number Mapping
(ENUM) working group, the purpose of which is to map E.164 numbers into the Do-
main Name System (DNS).
While the concept of ENUM is sound, it requires cooperation from the telecom industry
to achieve success. However, cooperation is not what the telecom industry is famous
for and, thus, far ENUM has foundered.

e164.org
The folks at e164.org are trying to contribute to the success of ENUM. You can log on
to this site, register your phone number, and inform the system of alternative methods
of communicating with you. This means that someone who knows your phone number
can connect a VoIP call to you, as the e164.org DNS zone will provide the IP addressing
and protocol information needed to connect to your location.
As more and more people publish VoIP connectivity information, fewer and fewer calls
will be connected through the PSTN.

DUNDi
Distributed Universal Number Discovery (DUNDi) is an open routing protocol de-
signed to maintain dynamic telecom routing tables between compatible systems (see
Chapter 14 for more information). While Asterisk is currently the only PBX to support
DUNDi, the openness of the standard ensures that anyone can implement it.
DUNDi has huge potential, but it is very much in its infancy. This is the one to watch.

Challenges

As is true with any worthwhile thing, Asterisk will face challenges. Let’s take a glance
at what some of them may be.

Too much change, too few standards

These days, the Internet is changing so fast, and offers so much diverse content, that it
is impossible for even the most attentive geek to keep on top of it all. While this is as

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