Angelo’s blog

I’ve been working on a project for quite some time now, and I’ve been making quite some progress.

My goal is to create a box that I can hook up between our existing (and expensive) Panasonic PBX and the PSTN, leveraging the benefits of VoIP and the flexibility of Asterisk, while preserving our investment and ease of use of the Panasonic PBX and phones.

Every now and then when I had some spare time, I worked on getting Asterisk to work with 2 ISDN cards, and I finally got it working. I was using a simple HFC-S card and a Dynalink IS64PH card, but I had some problems getting them to work in FreeBSD. I don’t think it’s a FreeBSD problem, just my lack of understanding of all these complicated ISDN thingies, and the lack of newbie-documentation wasn’t helping. 

So I installed Debian, since there’s a bit more documentation, and multiple frameworks (don’t know if that’s a good thing or a bad thing though). I first had to figure out the difference between isdn4linux, hisax, chan_isdn, and mISDN, and how they work together. Eventually, I got everything working, but the machine was bloated with different types of ISDN frameworks and software, different version of custom kernels, and too much unused crap. One card worked in hisax, one in mISDN, etc.

The next day, I bought 2 similar Sitecom DC-105 adapters for EUR 25 each. They use the HFC-S chipset as well, and they should work out of the box with mISDN. And besides that, if I want to replicate my configuration, I can just buy some more of these same cards, and use my existing config.

I installed the two new cards, slapped a clean install of Debian testing on the machine, recompiled the kernel, and installed mISDN and Asterisk 1.4, all in an hour or so (I had quite some practise the day before). Actually, it’s quite easy once you understand how mISDN works and how it cooperates with Asterisk.

I set one card to use TE mode, connecting to the public telephone network, and one cart in NT mode, connected with a cross cable to a NT1, and an ISDN phone connected to the NT1. Changing modes is done by just changing a simple value in the mISDN config file. Asterisk picks this up, and you can configure the ports quite easily in misdn.conf.

Now the hardware and the channels are all configured, I can start testing and developing the dial plan, the heart of Asterisk. I’ve allready got IAX softphones connected, some MP3 files for music on hold, now it’s playtime!