Monthly Archives: August 2008

Linksys SPA942 display string issues

I’ve recently built an Asterisk pabx to run all my phone systems for Amberdms. In testing I found everything to be working correctly, with the exception of my Linksys SPA942 desk phone.

The phone worked fine, except for when it received calls, the caller would not be able to hear anything, and the call would disconnect after 15 seconds everytime.

Further testing found that:

  • Calls from the Linksys to any phone (internal or external) worked fine.
  • Calls to & from software-based phones on the same network segment as the Linksys worked fine.

Whilst one-directional audio is typical of NAT issues, this wasn’t the case since the network was fully routed between the phone and the PABX.

After performing a packet dump on the local router, I found that the dumps showed RTP packets arriving at the phone from the PABX, but the phone was not returning any, meaning that the phone was not sending anything back!

After a long period of debugging, I enabled “sip set debug” on the PABX and found the following message in the output:

set_destination: Parsing <1000> for address/port to send to
[Aug 30 21:17:31] WARNING[14315]: chan_sip.c:5845 set_destination: Can't find address for host '1000'

I had configured the phone with the display string of “Jethro Carr <1000>”, and it seems that the “<1000>” was being interpreted by the PABX and used for the address of the phone – which explains the weird “can’t find adddress” messages I was receiving.

After changing the display string to just “Jethro Carr” the problem was resolved!

And so it begins….

Exciting news – From Mon 25th, I will now be working full time on my own business – Amberdms Ltd!

The next few months will involve a lot of heavy development work, as well as configuring a lot of the infrastructure that I currently have. I will need to upgrade my remaining CentOS 4 servers to CentOS 5 to gain Xen support and setup a high-HA cluster between my two production hosting servers.

And when I get time, I’ll need to add an RSS feed to this website, as it seems to be the one thing I keep getting pestered for. I’m also considering making some improvements and turning the code behind this site into an open-source package, so maybe I’ll set aside a day for some development work.

Whilst it generates quite simple/plain output, this website actually has an wiki-style interface allowing me to easily create and adjust pages, along with strong user/group permissions. Combining it with a javascript WYSIWYG editor of sometime could produce a nice simple wiki package with strong access control.

I’ll also be setting aside some time to upgrade my Libretto from Ubuntu 6.06 to Fedora 9. I recently picked up a second Libretto U100 laptop off trademe and have been trialing different distributions on it.

This will allow me to upgrade to Xorg 7.3 to gain the ability to use the new xrandr feature, which allows me to dynamically add external screens, and resize my desktop across them. With my existing Ubuntu 6.06 installation, I’ve never been able to get the laptop to output a 1680×1050 resolution for my widescreen LCD, but it works well with the latest intel driver and xrandr! :-)

Only problem outstanding is to try and find out why the laptop refuses to allow the external display to work, unless I boot the system with an external screen attached first – seems to be something to do with the toshiba_acpi module not being able to tell the BIOS to turn the external screen on/off.