asterisk users - Jun 2004 - sidetone noticeably loud on analog handsets on T100P

Hi guys,

I've run into a problem that I can't figure out on a bunch of handsets I
have running into a Rhino Equipment 24-port FXS channel bank hooked up 
to a T100P and running asterisk-0.9.0 and the associated stable Zaptel 
release.

The sidetone (your own voice that you hear in your handset, built in for 
comfort) is noticeably louder than it should be, and it doesn't seem to 
make any difference if I adjust the rx/txgain in zapata.conf (on either 
the inside Zap channels [handsets] or the external [POTS lines] ones 
(which are routed through another channel bank [Carrier Access AB I] and 
a separate T100P card).  What's also strange is that when I place a call 
from inside, the callee hears my voice fine and I can hear their voice 
with very little difficulty, but the my own sidetone is always too loud.

We've got regular analog handsets running into the Rhino channel bank 
and they seem to work fine for everything else, we've experimented with 
volume controls on the handsets themselves as well as on some 
Plantronics headsets that are plugged into them (but have also of course 
tested this scenario without the headsets for isolation).  The analog 
phones are known good by themselves and do not exhibit this behavior 
when directly plugged into a POTS line.

Has anyone experienced this?  I did some googling on it through the 
archives of course, but don't see much discussion of sidetone issues 
with analog handsets.

I'm wondering if there's some way I could be adjusting the sidetone in 
Asterisk or should I be looking at my FXS channel bank?

Thanks,

John Lawler

I noticed it on our most recent installation, where the customer
needed large display phones. We used Sayson 390s in that one through a
TE410P and an Adit 600 channel bank. I didn't think much of it, I just
figured I was too used to no sidetone on my cell phone and IP desk
phone. It seemed to be more than that of a POTS line with a phone
connected directly to it, but its been too long. Vonage/Asterisk at
home, work, and at many customer sites.

On Tue, 22 Jun 2004 18:17:42 -0500, john lawler
<asterisk-users.lists.digium.com@tgice.com> wrote:
> 
> Has anyone experienced this?  I did some googling on it through the
> archives of course, but don't see much discussion of sidetone issues
> with analog handsets.

> Has anyone experienced this?  I did some googling on it through the 
> archives of course, but don't see much discussion of sidetone issues 
> with analog handsets.
>
> I'm wondering if there's some way I could be adjusting the sidetone
in
> Asterisk or should I be looking at my FXS channel bank?
>
I have the same problem with an Adit 600 channel bank that I've been 
trying to resolve without
any success. The sidetone is loud and very annoying. The only way to 
avoid it is to keep the
phone mic further away from your mouth.

Unfortunately, I think it is a channel bank issue. I've disconnected my 
channel bank from
the Asterisk server and the sidetone is still very loud. I've changed 
the gain on the channel bank
but that hasn't made any difference.