On Wednesday 1 March 2006 11:15, Wolfgang Hottgenroth wrote: > > What I do not understand: When I connect my ISDN phone directly to the > NT, there is no echo. But it appears when asterisk/visdn comes into the > game. What does asterisk/visdn to introduce the echo? Is it the delay?
The echo is always present but, as long as it is not delayed, it is percieved as sidetone which is harmless and even desiderable. When you start introducing delay (because of VoIP packetization, long distance, codecs, etc..) the sidetone becomes hearable echo which is more and more audible and harmful as the delay grows. So, the rule is: before introducing delay you have to make sure you had already canceled the echo. (Actually the rule should be: "Thou shalt not introduce echo. Cancel your own echo!", but we have get the POTS network as it is :) Bye, -- Daniele Orlandi _______________________________________________ Visdn-hackers mailing list [email protected] https://mailman.uli.it/mailman/listinfo/visdn-hackers
