BE3000 / SPA8800 Echo Problem

[rmccoy]

I have a customer with a BE3000 using analog lines terminated with a SPA8800. There is no PRI in this installation. Users are complaining of hearing echo while on outside calls. Any thoughts on what I can fine-tune to eliminate the echo?

Ryan

[nalbert]

Ryan,

Could you give us details on the echo issues you are seeing

- Does it happen all the time or only some of the time?

- Does it happen only on specific phones? (if you do not know please test it out) What kind of phones do you have ? Are they on the latest firmware?

- Does it happen on specific lines? or all the lines? If you don't know it would be nice if you could test this out? Answer to this is essential to isolate the problem.

- Does it happen throughout the call or sometimes? Does it happen when people talk over each other? Does it happen to people that talk loudly?

The more details we have the better we can isolate it to a certain part of the network. Otherwise we would be shooting in the dark.

Navin Albert

[rmccoy]

It’s been hard to troubleshoot. The echo occurs most of the time and can occur randomly throughout a call. It doesn’t seem to be specific to any particular line. I’ll have to check if the problem is worse when a person speaks loudly.

[sanjsinh]

Hi Ryan

The parameter which controls the echo on line is Impedance on FXS port. You can tune this parameter and see if that helps. I do not know what value will be good. But the default value is tuned to work in US.

Thanks

[rmccoy]

Is it called Port Impedance?  This is the only one I see in the configuation.  It has many choices, do I go up or down/

[sanjsinh]

Pl. check following values on FXO port connection on BE3K UI:

Detect CPC: true

Detect Polarity Reversal: true

Detect PSTN Long Silence: false

Detect VoIP Long Silence: false

PSTN Long Silence Duration: 30

VoIP Long Silence Duration: 30

PSTN Silence Threshold: medium

Min CPC Duration: 0.2

Detect Disconnect Tone: true

SPA To PSTN Gain: -3

PSTN TO SPA Gain: 3

Ringer Impedance: High (Normal)

FXO Port Impedance: 600

On SPA8800 UI, under admin -> Advance -> Voice Tab -> Line Tab,

SPA To PSTN Gain: -3

PSTN TO SPA Gain: 3

If port impedance is set to 600, you may want to change it to 900 ohms. 600 works for most places, but some use 900.

Thanks

[rmccoy]

Thanks.  The only change was:

FXO Port Impedance: 600

I'll let you know how tomorrow goes. 

Ryan

[nalbert]

Ryan,

I have added some steps that can performed on the SPA 8800

https://supportforums.cisco.com/docs/DOC-26516

Please take a look.

[aherrera]

Hi Ryan,

Please let us know if you come across anything that helps. Have a client who's been experiencing the same for a couple months now.

Thanks,

Alberto

[rmccoy]

Cisco asked us to change the Port Impedance level. 

Connections | PSTN Connections.  Edit one of the FXO connections, click on Show Advanced.  Port Impedance is close to the bottom.

The default is supposed to be 600.  Mine was set to 270+750.  We ended up using 900 as the 600 setting still had echo.  Its better now but they still have Echo from time to time.

This needs to be changed for all FXO connections.

Ryan

[aherrera]

Hmm.. I wonder if that would help in our case.

Early on we also came across the mismatched Port Impedance setting; originally was set to 220+820. Switching to 600 helped a bit. After that we tweaked PSTN To SPA Gain; dropped it down to -3 (actually down to -6, but since there was no noticeable improvement, set back to -3). Eventually we swapped 6945 phones for 8945 phones.

Each step was better than the last, but, as in your case, they still have Echo from time to time. Most noticeable when both parties talk at the same time, by the way.

Regards,

Alberto

[jniblack]

We have echo on 6945 w 9.2.2.4 without a SPA.

The echo is heard by the outside party when the 6945 user is on speaker phone.  It is most prevalent when using an external conference bridge. 

Swapping an 8945 phone fixed it.

Jim

[nalbert]

I would have tried the latest version of 6945 and playing with the gain and attenutation settings a little bit.