[Asterisk-Users] mid-call echo

[Ryan Courtnage]

Henry Devito wrote:
> Although I am new to *, I have been working with VoIP for quite some time.
> Most of the time mid-call echo is do to PAD levels.  What type of
> trunks/lines are you using?

Just 4 analog phone lines.

If I understand the term 'PAD levels' correctly, you are suggesting the 
signal may need to be attenuated. In your experience, what sort of meter 
is used to check PAD levels, and what sort of device is used to correct 
them?  (ie: where can I buy these things?)

The tdm400p config file (zapata.conf) allows me to attenuate by using a 
negative 'rxgain' value.  In your opinion, do you I could acheive the 
proper 'padding' effect using this, or is whole point of padding to 
change the electrical properties by using inductors/resistors/capacitors?

Thanks for your help,
Ryan

> 
> -----Original Message-----
> From: asterisk-users-bounces at lists.digium.com
> [mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Ryan Courtnage
> Sent: Wednesday, September 29, 2004 9:21 PM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: [Asterisk-Users] mid-call echo
> 
> Hello all,
> 
> When it comes to echo cancellation, we have had great success using 
> zapata.conf's echo cancellation.  This eliminates the echo at the very 
> beginning of phone calls.
> 
> However, we now have a small office scenario where the users are hearing 
> the introduction of echo several minutes into a phone conversation 
> (where the first few minutes of the conversation sound fine):
> 
> PSTN <--> TDM400P+FXO (x4) <--> Uniden UIP200 (x4)