Echo analog lines connected to FXO ports - CME

[Gillepsie]

Hi, Brothers.

I´ve a Call manager express in a 2811 router with IOS version 12.4. I´ve had this platform installed since a couple of years ago but few months ago it started presenting echo in the FXO ports that I’ve configured with analog lines for communication with the PSTN. We were trying different CP tones and we diminish the echo intensity by that time, additionally we set eco canceller commands. However from some time ago the echo started again in an intermittent way when we make calls out to the PSTN. From 3 calls made, 2 have echo in the Cisco tier and the other one with no echo.

Below you can see the configuration on the FXO ports with the problem:

voice-port 0/0/0

trunk-group 1

supervisory disconnect dualtone mid-call

echo-cancel coverage 32

echo-cancel erl worst-case 3

cptone BE

timeouts call-disconnect 5

timing hookflash-out 50

connection plar 101

impedance complex2

description PBX_OFICINA BOSA

station-id number 7828470

caller-id enable

I sat tuned to any suggestion you can give me to fix this issue.

Regards,

[acampbell]

Hi

Looks like you are on the right track.

The echo heard by the ip phones is mostlikely being caused by the hybrids on the PSTN.

Please look at this link.

http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml

You need to try adjusting the echo cancellers in small steps but you must also shut/no shut the voice port between changes..

Hope this helps

Alex