I'm experience echo on outgoing calls: Snom 200 ----> Asterisk ----> T100P ----> PRI ----> called party I am getting echo on the Snom 200 phone. The called party does not hear the echo. Since the PRI is digital, I don't really understand where the echo is coming from. I turned on echotraining, echocancellation=yes (128), and echowhenbridged in zapata.conf, to no avail. Could it be the wiring? Any suggestions of where to go from here? tia, Mike ----------------------------------------------------------- Michael Schwartz mike@ziacom.us President (646)285-6841 Zia Communications http://www.ziacom.us
On Thu, 19 Aug 2004, Mike Schwartz wrote:> > I'm experience echo on outgoing calls: > Snom 200 ----> Asterisk ----> T100P ----> PRI ----> called party > > I am getting echo on the Snom 200 phone. The called party does not > hear the echo. > > Since the PRI is digital, I don't really understand where the > echo is coming from.Rule of thumb (i.e. a good starting point): if you hear the echo it is coming from somewhere else, your equipment mearly makes it noticable. In this case the echo is probably caused by an analog conversion at the remote party. This is quite common but for calls with a very short latency in the call path this is experienced as a reverb and not an echo. The voip leg probably introduces quite a few ms worth of latency and thus making the echo of your voice audiable. Since your digital end does not introduce any echo at all the remote party does not hear any echo even though the latency is the same in that direction. When a pstn circuit is so long that the delay is enought for the echo to be noticed an echo canceler is typically introduced from a pool automatically. Common points for these to be enabled are for international circuits etc.> I turned on echotraining, echocancellation=yes (128), and echowhenbridged > in zapata.conf, to no avail.There have been a few reports that too little cpu power makes the echo canceler misbehave. You may want to reduce the number of taps from 128 as there have been reports that this helps. Peter
> > I'm experience echo on outgoing calls: > > Snom 200 ----> Asterisk ----> T100P ----> PRI ----> called party > > > > I am getting echo on the Snom 200 phone. The called party does not > > hear the echo.> Rule of thumb (i.e. a good starting point): if you hear the echo it is > coming from somewhere else, your equipment mearly makes it noticable. In > this case the echo is probably caused by an analog conversion at the > remote party. This is quite common but for calls with a very short latency > in the call path this is experienced as a reverb and not an echo. >Reverb might be a good description. If this is the case--that my CLEC is the source of the echo/reverb when they do a digital to analog conversion, is there anything I can do about it, except try to cancel the echo? Can I ask them to change any settings? They have a 5E switch. My collo is right next door--I just cross connect to get my PRI. The echo I am experiencing is on local calls. My * server is a dual-processor XEON (2.4 Ghz) Supermicro server. Its relatively fast. I will reduce the number of taps, and I was also thinking of decreasing the sample size on the phone from 20ms to 10ms. thanks a lot! - Mike ----------------------------------------------------------- Michael Schwartz mike@ziacom.us President (646)285-6841 Zia Communications http://www.ziacom.us
On Thu, 19 Aug 2004, Mike Schwartz wrote:> > Rule of thumb (i.e. a good starting point): if you hear the echo it is > > coming from somewhere else, your equipment mearly makes it noticable. In > > this case the echo is probably caused by an analog conversion at the > > remote party. This is quite common but for calls with a very short latency > > in the call path this is experienced as a reverb and not an echo. > > > > Reverb might be a good description.Normally it is called reverb if it is close enough in time not to be annoying and echo otherwise. Your description sounds like it just crossed the border. :-(> If this is the case--that my CLEC is the source of the echo/reverb when they do > a digital to analog conversion, is there anything I can do about it, except try > to cancel the echo? Can I ask them to change any settings? They have a 5E > switch. My collo is right next door--I just cross connect to get my PRI. > > The echo I am experiencing is on local calls.The likliest source of the echo is one of the two endpoints for the analog loop to the far en subscriber. I.e. either the far end phone or the far end pstn connection with the phone being more likely. There is little the pstn operator can do except place an always activated echo canceler on yuor connection. I have read that those are still expensive resources and normally reserved for long distance calls where the pstn itself introduces a large latency.> My * server is a dual-processor XEON (2.4 Ghz) Supermicro server. Its > relatively fast. I will reduce the number of taps, and I was also thinking of > decreasing the sample size on the phone from 20ms to 10ms.The latter can probably get you into the nice reverb latency. Please post your results! I think asterisk gives you some debug info saying if echo canceling is enabled or not for a call. Do you see anything on the console? Peter -- Peter Svensson ! Pgp key available by finger, fingerprint: <petersv@psv.nu> ! 8A E9 20 98 C1 FF 43 E3 07 FD B9 0A 80 72 70 AF ------------------------------------------------------------------------ Remember, Luke, your source will be with you... always...