Page 498 - Asterisk™: The Future of Telephony

codecs.conf

Most codecs do not have any configurable parameters; they are what they are, and
that’s all they are.
Some codecs, however, are capable of behaving in different ways. This primarily means
that they can be optimized for a particular goal, such as cutting down on latency, mak-
ing best use of a network, or perhaps delivering high quality audio.
The codecs.conf file is fairly new in Asterisk, and as of this writing it allows configuration
of Speex parameters only. The settings are self-explanatory, as long as you are familiar
with the Speex protocol (see http://www.speex.org).
codecs.conf also allows you to configure Packet Loss Concealment (PLC). You need to
define a [plc] section and indicate genericplc => true. This will cause Asterisk to
attempt to interpolate any packets that are missed. (Enabling this functionality will
incur a small performance penalty.)

dnsmgr.conf

This file is used to configure whether Asterisk should perform DNS lookups on a regular
basis, and how often those lookups should be performed.

dundi.conf

The DUNDi protocol is used to dynamically look up the VoIP address of a phone
number on a network, and to connect to that address. Unlike the ENUM standard,
DUNDi has no central authority. The dundi.conf file contains DUNDi extensions used
to control what is advertised; it also contains the peers to whom you will submit lookup
requests and from whom you will accept lookup requests. The DUNDi protocol was
explored in Chapter 14.

enum.conf

The Electronic Numbering (ENUM) system is used in conjunction with the Internet’s
DNS system to map E.164 ITU standard (ordinary telephone) numbers to email ad-
dresses, web sites, VoIP addresses, and the like. An ENUM number is created in DNS
by reversing the phone number, separating each digit with a period, and appending
e164.arpa (the primary DNS zone). If you want Asterisk to perform ENUM lookups,
configure the domain(s) in which to perform the lookups within the enum.conf file. In
addition to the official e164.arpa domain, you can have Asterisk perform lookups in
the publicly accessible e164.org domain.

470 | Appendix D: Configuration Files