System information

these applications is the MeetMe() application. The SLA applications come with the
same module as the MeetMe() application, so you must install the app_meetme module.
You can check at the Asterisk CLI to see if you already have the module:
pbx*CLI> module show like app_meetme.so
Module Description Use Count
0 modules loaded
In this case, the module is not present. The most common reason that an Asterisk
system does not have the app_meetme module is because DAHDI has not been installed.
The MeetMe() application uses DAHDI to perform conference mixing. Once DAHDI is
installed (refer to Chapter 3 for installation information), rerun the Asterisk configure
script, recompile, and reinstall. Once the module has been properly installed, you
should be able to see it at the CLI:
*CLI> module show like app_meetme.so
Module Description Use Count
app_meetme.so MeetMe conference bridge 0
1 modules loaded
Once the app_meetme module is loaded, you should have both the SLAStation() and
SLATrunk() applications available:
*CLI> core show applications like SLA
-= Matching Asterisk Applications =-
SLAStation: Shared Line Appearance Station.
SLATrunk: Shared Line Appearance Trunk.
-= 2 Applications Matching =-
Configuration Overview
The two main configuration files that must be edited to set up SLA are /etc/asterisk/
extensions.conf and /etc/asterisk/sla.conf. The sla.conf file is used for defining trunks
and stations. A station is any SIP phone that will be using SLA. Trunks are the literal
trunks or shared extensions that will be appearing on two or more stations. The Asterisk
dialplan, extensions.conf, provides some important glue that pulls an SLA configuration
together. The dialplan includes some extension state hints and extensions that define
how calls get into and out of an SLA setup. The next few sections provide detailed
examples of the configuration for a few different use cases.
Key System Example with Analog Trunks
This usage of SLA comes with the simplest configuration.
†
This scenario would typi-
cally be used for a fairly small installation, where you have a few analog lines and SIP
† Admittedly, none of the configuration for SLA is simple.
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