Asterisk Linksys NSLU2

Asterisk on Linksys NSLU2

The Linksys NSLU2 (Network Storage Link for USB 2.0 Disk Drives) is a Network-attached storage (NAS) device that has user-modifable firmware.

As usual there's more than just one way to play with Linux (and Asterisk) on a slug:

Asterisk is available now for Linksys NSLU2 using customized firmware. You have to install first the unslung software before installing the asterisk package:

Look here:
This includes a description of how to get a HFC-S USB ISDN adapter working - how neat!

Debian Sarge
Look here: (no Asterisk specifics)

"Unslung" Installation

This is a step for step guide for enabling Asterisk in your Linksys NSLU2 ("Slug").
Following the guide will not change the default features of your device, it will just add some nice functionality to it.


All you need is :
  1. Unslung Firmware from
  2. ipkg Package "asterisk"

The firmware IS required. You will NOT get the steps below working if you use the stock firmware.
The firmware on your device can be upgraded using the web interface. Please consult your users manual
for details.

Installing Firmware

Follow the instructions you can find at

You should not use firmware older than Unslung 3.18.

Getting access

Enable "telnet" using the instructions you can find at

Unslung it

Follow the instructions for replacing the ramdisk by a physical filesystem on an external drive. You should not try to install packages with the default ramdisk. If you do not want to install a harddisk drive you can use an USB-stick instead.

Install Asterisk package

/opt/bin/ipkg update < enter >
/opt/bin/ipkg install asterisk < enter >

Now you can put your asterisk configuration files at /opt/etc/asterisk. You can find sample configuration files (which are NOT optimized for embedded devices!!) at /opt/etc/asterisk/sample

Due to the limited resources on embedded devices, it is recommended to reduce the footprint of Asterisk by eliminating unneeded modules, see Asterisk Slimming

You can find additional information about the NSLU2 asterisk package installation here:

NSLU2-Asterisk mailing list

The users of asterisk on NSLU2 have now their own mailing list:

Start Asterisk

/opt/sbin/asterisk -cvvv

Provisioning a Cisco 79XX Phone with the NSLU2

Since the NSLU2 can act as a TFTP and HTTP server, it makes a great platform for a small Asterisk system that can also provision IP phones such as the Cisco 79XX series. With such a setup you can have a shared dialing directory, centralised configuration, custom ring-tones, custom screen backgrounds, MWI (message waiting indicators) and many other goodies. You can find additional information about configuring the NSLU2 to provision a Cisco 7940 (similar for all 79XX series) here:

In addition, further information about configuring Cisco 79XX phones are located on this site.


Currently the codecs g723, iLBC and g729 are not supported (would require floating point processor/emulation or would have to be replaced by an integer implementation of the codec).
The performance is sufficient for home/SOHO use - eg. a few lines using SIP and IAX. The slug's IXP400 should have enough horse power for a home PBX with up to 4 lines, when less CPU intensive codecs (like GSM and 711u) are used.

See also:

Go back to Asterisk

Created by: cdoban, Last modification: Thu 24 of Jul, 2008 (02:13 UTC) by admin
Please update this page with new information, just login and click on the "Edit" or "Discussion" tab. Get a free login here: Register Thanks! - Find us on Google+