Kristof Hardy wrote:
The problem has been consistent from 1.0 through CVS to 1.2, and
across different machines and distributions. Does anyone have any
suggestions on how I can deal with this? I have had echo cancellation
happening, but half-duplex speech is not acceptable.
You're not using zaptel, what are you using to connect to the outside?
(and is it PSTN/ISDN ?)
Can you advice on what hardware you're running, that would help..
I'm running Voicetronix hardware, the OpenSwitch 12 as 8 FXO and 4 FXS,
connecting to the PSTN. The vpb software echo canceller does actually work
somewhat, but it takes a long time to train, and if you stop talking for 30
seconds it untrains.
But really, I shouldn't be getting echo at all - my hybrids are tuned right
for Australian phones, and using the voicetronix measerl (measure echo
return loss) utility I see a max of -10db.
Call path |Echo heard on|Echo recorded?
=====================================+=============+==============
landline FXO->asterisk->FXO mobile | both | both
FXS->asterisk->FXO mobile | FXS | FXS
SIP->asterisk->FXO anything | SIP | SIP
landline FXO->asterisk->FXS | both ends | both
landline FXO->asterisk->SIP | SIP | no
mobile FXO->asterisk->SIP | SIP | SIP
FXS->asterisk->FXO landline | both ends | FXO
landline FXO->asterisk->FXO landline | both ends |
SIP->asterisk->SIP | none | none
FXO landline is our current key system PBX, FXS is a little Jackson dialpad
and headset, FXO mobile is calling out on an FXO through the PSTN to a GSM
mobile.
In all cases, it's just the local end that hears themselves echoing.
What I want to know is why I'm seeing such long echos, of 180ms or more -
from what I understand, packetisation delays should only be tens of
milliseconds. It's not PSTN delay either - I'm calling lines on the local
exchange. I'm at a loss to explain where it's coming from.
--
James Andrewartha
Systems Administrator
Data Analysis Australia Pty Ltd
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