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

[John Daragon]

jennyw wrote:
> Hi,
> 
> We recently tried installing Asterisk for a small office. We figured the 
> safest way to go would be to buy from someone who sold equipment 
> specifically for Asterisk and to use a consultant that they 
> recommended.  However ... it didn't turn out so great.  Sound quality is 
> terrible -- the echo is pretty bad, and there are popping noises, too. 
> Callers say that people on the Asterisk end sound very faint, while 
> people on the Asterisk end hear people maybe too loundly (might be 
> related to the popping noises -- sounds like when you have stereo turned 
> up too high).  The reseller and the consultant both say that the most 
> likely cause for this is using Digium cards w/ analog phone lines. 
> Apparently, they say, sound quality can be pretty bad.
> 
> I called Digium and they gave me some suggestions for settings, but 
> nothing has worked well. So I wanted to ask others ... has anyone had 
> good luck with using analog phone lines and Asterisk? Especially with 
> Digium cards (we use the TDM400P)? Although from reading articles on the 
> net it sounds like people do have a lot of echo problems, it also sounds 
> like some people are using analog phone lines with some success.
> 
> FYI, what I've mainly done is try changing echotraining, echocancel, 
> echocancelwhenbridged, txgain, and rxgain in zapata.conf. I've heard 
> from the reseller that what might work better is to trade the Digium 
> cards in for VegaStream gateway. It's more expensive, but apparently has 
> a DSP built in that should increase voice quality. Of course, they say 
> there are no guarantees with this.  They also mentioned (after the fact) 
> that Asterisk systems don't necessarily save money. So far, the 
> experience has been very frustrating and I'd love to hear some success 
> stories from others (or more info on what I can realistically expect 
> from an Asterisk system)! And, of course, some ideas on how I can get 
> things to work better.
> 
> One of the next tests will be using Asterisk with a VoIP provider to see 
> what the sound quality is like with digital on both ends. PRI sounds 
> like it'd be even better, but for an office w/ 5 people, it sounds 
> pretty expensive. How do other people do this?

I started using Asterisk for my own small business about a year ago.

Externally we have a single analogue PSTN line (it's the house one...), 
an ISDN2e connection and an IAX2 connection (over 20:1 256/512kbps ADSL) 
with a DID in central London. The analogue line comes in to an old 
X100P, and the ISDN into an AVM Fritz! passive card.

Internally, we have a TDM400 which talks to analogue phones in the 
house. In my office (which is in a different building) we have a mixture 
of Snom and ipDialog phones and a Grandstream ATA attached to a fax machine.

We get a little echo on the ipDialog phone (but not enough to be a 
problem) when we talk to people on analogue phones. One of the handsets 
  attached to the TDM400 is a DECT phone, and there's a little flurry of 
training noise at the beginning of an incoming call, but after that the 
quality is good to perfect.

I'm just beginning to sell Asterisk systems. I agree that for some 
installations, it doesn't really make economic sense. In the UK, at 
least, you have to fall into a specific band of numbers-of-users and 
minutes-per-month for IP telephony to show a saving. Some of the small 
3-line-8-extension systems from (say) Panasonic will be cheaper than 
Asterisk once the hardware is bought and the time (or consultancy) 
applied. Of course, these systems don't have much in the way of 
flexibility or features, and I'm talking at the moment to a company that 
has three sites, is using Cisco's Call Manager, and has an Asterisk 
system merely to convert the H.323 from the Cisco to IAX2.  In this 
case, * could replace the CCM system in its entirety.

By the time you have 100 users, * is a no-brainer in economic terms. 
Small users only really save (IMHO) if they a) use an awful lot of 
minutes (or call abroad a lot), b) need flexibility of features, or c) 
need internal control.

Of course there may be local or exceptional circumstances which make 
this all a load of rubbish ! YMMV.

Oh, and on echo; read :

http://lists.digium.com/pipermail/asterisk-users/2005-March/096754.html

jd

-- 

John Daragon                                          john at argv.co.uk
argv[0] limited
Lambs Lawn Cottage,  Staple Fitzpaine,  Taunton,  TA3 5SL,  UK
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