Asterisk, the VoIP Server on DD-WRT

I'm a big fan of Asterisk on router -- imho, it's the perfect platform for anyone want to try Asterisk at home -- 24x7, fanless and even the cheapest router can handle at least 2-3 concurrent conversation. Before this WZR-HP-G300NH, I had Asterisk running on a WRT54G-TM for over a year with lots of fun.

Installing Asterisk on the router is easier now as current OpenWrt trunk build(the one we use) includes prebuilt Asterisk binaries. As always, since OpenWrt is designed to work with / not /opt, some adjustment is required to get Asterisk working properly.

1. Install Asterisk 1.6
   Believe it or not, DD-WRT MEGA also has Asterisk included -- it's an old ver1.4 and some important files are missing -- I have no idea why DD-WRT decided to do so, too much flash ROM? Anyway, to install Asterisk 1.6 on our opkg enabled router, run
   opkg install asterisk16
   
   You may also want to install some additional modules like:
   opkg install asterisk16-res-agi
   opkg install asterisk16-res-musiconhold
   
   To view a full list of Asterisk packages(lots of them!), run
   opkg list | grep asterisk16
   
   
2. The configuration file: asterisk.conf
   With our installation, the asterisk.conf is in /opt/etc/asterisk/asterisk.conf. Change it to the contents below:
   
   [directories] ; remove the (!) to enable this
   astetcdir => /opt/etc/asterisk
   astmoddir => /opt/usr/lib/asterisk/modules
   astvarlibdir => /opt/usr/lib/asterisk
   astdbdir => /opt/usr/lib/asterisk
   astkeydir => /opt/usr/lib/asterisk
   astdatadir => /opt/usr/lib/asterisk
   astagidir => /opt/usr/lib/asterisk/agi-bin
   astspooldir => /var/spool/asterisk
   astrundir => /var/run/asterisk
   astlogdir => /var/log/asterisk

[compat]
pbx_realtime=1.6
res_agi=1.6
app_set=1.6

As you can see, by modifying this file, we tell Asterisk to look for files at /opt/etc/asterisk and /opt/usr/lib/asterisk instead of default locations, which fits our installation.

Now try to launch asterisk by running:
asterisk -vvvvvc
Exit by pressing ctrl+c



3. Asterisk configuration
   By default, asterisk loads lots of modules, you can change the settings to fit your needs and reduce memory usage.
   
   Below is a sample of /opt/etc/asterisk/modules.conf with reduced modules:
   
   [modules]
   autoload=no                ; only load explicitly declared modules
   load => app_dial.so
   load => app_echo.so
   load => app_macro.so
   load => app_playback.so
   load => chan_sip.so
   load => codec_ulaw.so
   load => pbx_config.so
   load => format_pcm.so
   load => format_wav.so
   load => func_callerid.so
   load => func_strings.so
   load => res_musiconhold.so
   load => res_agi.so
   
   For SIP users, other important files including /opt/etc/asterisk/extensions.conf and /opt/etc/asterisk/sip.conf. These are not covered here, please refer to website about Asterisk like asteriskguru and voip-info.org. Also, here is a must-read  ebook: Asterisk: The Future of Telephony Second Edition(download the PDF book)
   
   
4. Run it as service
   Create file /opt/etc/init.d/asterisk with below(delete previous contents if its not empty)
   
   source /mnt/root/.profile
   mkdir -p /var/run/asterisk
   mkdir -p /var/spool/asterisk
   mkdir -p /var/log/asterisk/cdr-csv
   /opt/usr/sbin/asterisk -C /opt/etc/asterisk/asterisk.conf
   
   And run
   chmod a+x /opt/etc/init.d/asterisk
   ln -s /opt/etc/init.d/asterisk /opt/etc/init.d/S95asterisk
   

That's all. Enjoy Asterisk and happy VoIP!