[Asterisk-Users] E1 Echo

[Florian Overkamp]

Hi,

Rich Adamson wrote:
>>I am beginning to wonder whether what echo IS heard is being caused by
>>packetisation delays "in the network" - The default tap length is 128,
>>or I believe 16ms. If something in the PSTN causes a delay more than
>>that length (no idea what might cause that) then echo would still be
>>heard.

We have found that a relatively innocent change by the local incumbent 
operator has forced us to modify our pstn gateways to change from 128 
taps to 256 taps. Since th

>>Does anyone have any experience in this area? Any ideas? How "heavy
>>handed" would it be to increase the tap length to 256? I have not seen
>>anyone suggest that this might be a good idea.

There have been a few issues especially related to the echotraining 
section (which can go boo-boo on E1 lines because the audio path is not 
always entirely complete when zaptel expects it to). If you make sure 
you are on recent zaptel EC standards you can up to 256 taps. There will 
be a minor residue that needs work, but it will allow a lot of room to 
decrease the loss-plan you may be using now.

Florian.