I know echo cancellation is a popular topic from reading all the posts, faqs etc. I can find. However I still can’t get rid of some annoyingly large echos.
Have a Debian box with:
ii asterisk 1.2.13~dfsg-2 Open Source Private Branch Exchange (PBX)
ii zaptel 1.2.11.dfsg-1 zapata telephony utilities
The X100P is recognised. I’ve made sure I’m using the right impedance settings for the UK:
Zapata Telephony Interface Registered on major 196
Zaptel Version: 1.2.11 Echo Canceller: MG2
wcfxo: DAA mode is 'CTR21’
Found a Wildcard FXO: Wildcard X100P
Registered tone zone 4 (United Kingdom)
You can see that MG2 is the echo canceller in use. However when I connect any SIP extention to the ZAP line, either calling out or calling in, I get a large delay echo on my side. The other party hears no echo.
From tapping the microphone and listening the round trip time for the echo seems to be in the order of 300ms. Seems to me way longer than the echo cancellers can cope with. I’ve played around with tx and rx gains and echo canceller parameters but the mest I can manage is that the echo occasinally fades to a crack as I talk. However its always there when you start speaking which, of course, has the effect of stalling the speech centre of your brain and you have to… stop… and…start.
Any clue would be great as this is only thing preventing me unplugging all my PSTN direct wire phones.