[Asterisk-Users] Small office setup/using analog lines w/ Asterisk

jennyw jennyw at dangerousideas.com
Sun Aug 21 17:06:30 MST 2005


Thanks, everyone, for your suggestions. I'm going to stop by the office 
tomorrow to try some of these out.

Here's more info on the setup: We bought a brand new computer for this 
-- I don't have the specifics right now, but will look that up in the 
office tomorrow. We have two Digium cards -- a TDM04B and a TDM01B.  
This system supports two organizations sharing the same office space: 3 
lines go to one org., the other 2 go to the other.

The Digium cards actually are sharing IRQs with other devices -- the 
installer mentioned it could be an issue initially, but when he saw that 
the devices that the cards were sharing with were the network card and 
the video card, he said to just try and see if it works first. Sounds 
like some of the problems that we're having could be related to this, 
and it's probably the first thing I should try changing.

I have tried using ztmonitor to adjust the txgain and rxgain. It was 
very frustrating ... changing the tx to higher or lower values did not 
necessarily change it in the direction you'd think. Also, changing rx 
sometimes affected tx and vice versa. In the end, I gave up because 
nothing I did increased sound quality -- although it wasn't so hard to 
make things worse. Any hints here?

We're using Sipura phones. We realize these aren't has high quality as 
Polycoms, but this was what the manger decided to get based on the 
budget. We're spending more than originally anticipated now because of 
the problems we're having, but it seems like the Digium cards are a more 
likley culprit than the Sipura phones.  However, if there's a way to 
isolate problems, that'd be great. I guess one thing is we could try 
more experiments with one extension calling another -- if the sound 
quality is a lot better, then it's unlikely a problem with the Sipura 
phones. If the sound quality is poor, I'll try hooking up the phones to 
a new network card.

As for interference ... we don't have wireless devices, and the main 
phone we're testing with is about 10' away from the switch. I suppose 
there's still some possibility with interference, but I think it's 
something I'll prioritize a little lower.

One additional question -- are VoIP lines generally easier to get going 
w/ good sound quality than POTS lines? One reason we went with POTS was 
for sound quality. Of course, we also figured it'd be more reliable than 
DSL, which was the main reason for going with POTS lines. Right now we 
use 5 POTS lines ... if VoIP sounds better, we were thinking of dropping 
three of those lines and getting VoIP lines, keeping the POTS lines as 
backup. Any thoughts on that plan? One thing I'm not sure about is how 
to select the POTS lines from the phone sets. I suppose we could assign 
a second extension to the phones (they support 2) and have the second 
one be POTS and the first be VoIP. Another thing I was wondering is 
whether we could get hunting to work properly with a mix of VoIP and 
POTS. I'll call the phone company tomorrow, but if anyone has tried 
anything like this, I'd like to hear about it.

Also, are there any VoIP vendors that work particularly well with 
Asterisk? I've seen Broadvoice mentioned a bit ... are they a good 
company for this?  I'd love a company that could do automatic failover 
-- if the VoIP line cuts out, transfer to an analog phone line (I know 
Vonage has a feature like this, but they're expensive and we don't need 
a lot of the features).

Thanks again for all the suggestions!

Jen





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