[TriLUG] Some basic * questions

[Mark Turner]

Comments below.

Brian Henning wrote:

> I figure the easiest way is to set up an Asterisk server here, attach it 
> to our existing PBX to show up as another extension, and push an 
> asterisk session (is that good terminology?) through an SSH tunnel (or 
> is that a bad idea?) to the remote employee's broadband-equipped 
> machine, which will sport a cheap headset/boom mic arrangement.

As Ron pointed out, SSH does TCP forwarding. You should check into 
OpenVPN, as it can handle both TCP and UDP.

> So, my quick questions:
> 1 - Interface card.  What's a good tradeoff between cheap and 
> reliable/quality/ease-of-use?  

In VoIP, as with other things, you often get what you pay for (though, 
uh, Linux is the exception!). Steer clear of cheap hardware.

You need a Digium Wildcard with a few FXS modules, depending on how many 
extensions you want to forward. You'll need a Nortel ATA to drive them, 
which you may already have if you now have a fax connected to your 
Nortel system.

> 2 - Server.  I suspect that an Asterisk installation that only has to 
> handle one call at a time shouldn't need a lot of horsepower.  What are 
> some minimum specs I should be aware of?

You can be assured any machine with a 1 GHz processor or better will 
work just fine. You can even go below this and be fine, though finding a 
slower machine nowadays is a challenge.

> 3 - Client-side.  What's the best PC-based client-side software to use 
> to interface with the IP side of Asterisk?  Must work in Windows and be 
> VERY easy to configure.

I like X-Lite. Great quality, free, and multi-platform:
http://www.xten.net/index.php?menu=download

> 4 - Bandwidth.  The remote employee is on some flavor of cable-based 
> broadband, and we're currently on 1.5m/384k (or thereabouts) ADSL.  We 
> don't currently shove a lot of data up that pipe (most of the time), but 
> how much bandwidth does one call require?  8k is nibbling at the back of 
> my mind..

An uncompressed G.711 channel is roughly 80kbps. There are G.729 
licenses you can buy from Digium which will compress that to around 
16kps or so (Jon, help me out here). The freeware Linux version of 
X-Lite doesn't support G.729, but if your users are of the Windows 
variety, you can buy the G.729 version of X-Lite inexpensively.

Mark
www.markturner.net