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Echo PSTN Calls

Echo PSTN Calls

Echo PSTN Calls


I have a VoIP network with a CCM 4.1(3) and a Cisco 2801 Router. Sometimes, when a call is made or recieved to and from the PSTN, i hear my own voice even laughter than my peer on the other side of the phone. How can it supress this echo?

Thanks in advanced
Alfredo Zazueta

RE: Echo PSTN Calls

Are you on a headset or handsfree by any chance?
make sure your volume is not turned up too high which would cause exactly what you described.
on the phone itself make sure that the volume is set to about 1/2 or a tad over at the most.  

RE: Echo PSTN Calls

I don't know Cisco's but I agree with t above comments. We use Aastra phones and if they ramp up the volume to more than about 50% you can start getting echo./
We counteracted this to some degree by putting the sidetone right down (but be careful, to low and people start shouting and doing other odd behaviour)

Robert Wilensky:
We've all heard that a million monkeys banging on a million typewriters will eventually reproduce the entire works of Shakespeare. Now, thanks to the Internet, we know this is not true.


RE: Echo PSTN Calls

If the echo is only heard intermittently, it may be due to echo being reflected back from somewhere in the PSTN. Since that 'path' is not used on every call, you won't hear the echo on every call. In this case, you might need to configure a reduction of input gain and an increase in output attenuation on the voice port(s). The intent is to lower the reflected echo energy enough that the echo canceller will be able to recognize it as echo and not original incoming voice energy. Then the EC can knock it down.

You might try input gain -3 and output attenuation 3 ... good starting point.

Be alert to any reports from users about incoming audio sounding too low...or outside parties commenting about lower audio. 3dB probably won't cause that. But be aware.


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