[on-asterisk] Polycom Echo Problems
Hi All: I'm having a problem with a customer that has a bunch of Polcom 501 and 601 sets. They are complaining about echo. Does anyone have some suggestions for some good settings for AEC and AES in sip.cfg for the Polys? Any other suggested settings or changes to the stock sip.cfg? Thanks, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you.
Re: [on-asterisk] Polycom Echo Problems
Intermittently, both have the echo. They have other other sets in the office not experiencing the echo problem. Their PSTN connection has been properly tuned for echo (via Milliwatt, etc). I'm just looking for a good config for AEC and AES on the Polys (and perhaps gains). By default they are turned off in the stock sip.cfg - Original Message - From: Jim Van Meggelen [EMAIL PROTECTED] To: 'Bill Sandiford' [EMAIL PROTECTED]; asterisk@uc.org Sent: Friday, July 13, 2007 12:30 PM Subject: RE: [on-asterisk] Polycom Echo Problems Couple of things that need to be known: Who has the echo? Your users? or the people who are calling them? How does the system connect to the outside world? (PSTN) Jim -Original Message- From: Bill Sandiford [mailto:[EMAIL PROTECTED] Sent: July 13, 2007 12:23 PM To: asterisk@uc.org Subject: [on-asterisk] Polycom Echo Problems Hi All: I'm having a problem with a customer that has a bunch of Polcom 501 and 601 sets. They are complaining about echo. Does anyone have some suggestions for some good settings for AEC and AES in sip.cfg for the Polys? Any other suggested settings or changes to the stock sip.cfg? Thanks, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: [on-asterisk] Polycom Echo Problems
Couple of things that need to be known: Who has the echo? Your users? or the people who are calling them? How does the system connect to the outside world? (PSTN) Jim -Original Message- From: Bill Sandiford [mailto:[EMAIL PROTECTED] Sent: July 13, 2007 12:23 PM To: asterisk@uc.org Subject: [on-asterisk] Polycom Echo Problems Hi All: I'm having a problem with a customer that has a bunch of Polcom 501 and 601 sets. They are complaining about echo. Does anyone have some suggestions for some good settings for AEC and AES in sip.cfg for the Polys? Any other suggested settings or changes to the stock sip.cfg? Thanks, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: [on-asterisk] Polycom Echo Problems
Echo *always* comes from the far end point. The amount a given person perceives the echo is determined by how loud and how delayed the echo is. Volume and delay are influenced by a number of factors along the call path. Echo is a very complex issue but I'll try and give a brief explanation. In the situation where you have a Polycom phone connected to an Asterisk server which is in turn connected to the PSTN talking to a residential wireline customer, e.g.: Polycom -- Asterisk -- PRI -- Wireline Handset If the Polycom customer hears echo it's coming from the wireline handset (and/or the hybrid but I'm trying to keep this example simple). Most consumer handsets just don't care about generating echo because its never been a problem. So echo is normal on all local wireline calls but you don't perceive (hear) echo because the echo is not delayed. Now when you throw Asterisk in the mix the act of encoding and decoding the voice adds delay. This added delay causes you to perceive echo even though the volume of the echo is roughly the same. Technically, to solve echo you fix the endpoint that's causing the echo. But since you can't replace every wireline phone ever made and the telco certainly isn't going to help you that isn't a practical solution. The best you can do is put an echo canceler as close as you can to the endpoint and in this case it's on the Asterisk box. Unfortunately Asterisk's standard built in echo cancelers are crap. They don't even come close to reaching the level of the ITU G.164 standard for echo cancel. That is why you buy cards with add-on hardware echo cancelers that meet the G.164 standard (Sangoma, Digium). Recently you can also buy add-on software echo cancellation from both Sangoma Digium which meet the G.164 standard but beware it exacts a heavy toll on your CPU. But depending on call volume and hardware it might work just fine for you. All of this is a long winded way of saying; you can tune your phone settings until your blue in the face but you won't get rid of the echo. Sorry. So to prove my theory conduct the following tests: Polycom -- Polycom (no echo) Polycom -- Cell phone (no echo) (cell phones do extensive echo cancel) Polycom -- Longdistance (no echo) (telcos do echo cancel on LD) Polycom -- wireline residential (echo!!) That is why your customer reports intermittent echo problems. Hope the above helps you out. John On Fri, 2007-07-13 at 12:51 -0400, Bill Sandiford wrote: Intermittently, both have the echo. They have other other sets in the office not experiencing the echo problem. Their PSTN connection has been properly tuned for echo (via Milliwatt, etc). I'm just looking for a good config for AEC and AES on the Polys (and perhaps gains). By default they are turned off in the stock sip.cfg - Original Message - From: Jim Van Meggelen [EMAIL PROTECTED] To: 'Bill Sandiford' [EMAIL PROTECTED]; asterisk@uc.org Sent: Friday, July 13, 2007 12:30 PM Subject: RE: [on-asterisk] Polycom Echo Problems Couple of things that need to be known: Who has the echo? Your users? or the people who are calling them? How does the system connect to the outside world? (PSTN) Jim -Original Message- From: Bill Sandiford [mailto:[EMAIL PROTECTED] Sent: July 13, 2007 12:23 PM To: asterisk@uc.org Subject: [on-asterisk] Polycom Echo Problems Hi All: I'm having a problem with a customer that has a bunch of Polcom 501 and 601 sets. They are complaining about echo. Does anyone have some suggestions for some good settings for AEC and AES in sip.cfg for the Polys? Any other suggested settings or changes to the stock sip.cfg? Thanks, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you. No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.476 / Virus Database: 269.10.4/898 - Release Date: 12/07/2007 4:08 PM - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional
Re: [on-asterisk] Polycom Echo Problems
John: Thanks for the description, it is very good. Here is the scenario in which this customer is experiencing echo. Polycom --- Asterisk --- Internet --- Polycom also Polycom --- Asterisk --- IX Private Line (delay 10ms) --- Polycom also Polycom --- Asterisk SIP Trunk to carrier --- Carrier's CLASS 5 --- PSTN This particular customer is seeing echo in all three scenarios. Hence the reason I'm looking into the AEC and AES features of the Polycom. Bill - Original Message - From: John Lange [EMAIL PROTECTED] To: asterisk@uc.org Cc: [EMAIL PROTECTED] Sent: Friday, July 13, 2007 4:38 PM Subject: Re: [on-asterisk] Polycom Echo Problems Echo *always* comes from the far end point. The amount a given person perceives the echo is determined by how loud and how delayed the echo is. Volume and delay are influenced by a number of factors along the call path. Echo is a very complex issue but I'll try and give a brief explanation. In the situation where you have a Polycom phone connected to an Asterisk server which is in turn connected to the PSTN talking to a residential wireline customer, e.g.: Polycom -- Asterisk -- PRI -- Wireline Handset If the Polycom customer hears echo it's coming from the wireline handset (and/or the hybrid but I'm trying to keep this example simple). Most consumer handsets just don't care about generating echo because its never been a problem. So echo is normal on all local wireline calls but you don't perceive (hear) echo because the echo is not delayed. Now when you throw Asterisk in the mix the act of encoding and decoding the voice adds delay. This added delay causes you to perceive echo even though the volume of the echo is roughly the same. Technically, to solve echo you fix the endpoint that's causing the echo. But since you can't replace every wireline phone ever made and the telco certainly isn't going to help you that isn't a practical solution. The best you can do is put an echo canceler as close as you can to the endpoint and in this case it's on the Asterisk box. Unfortunately Asterisk's standard built in echo cancelers are crap. They don't even come close to reaching the level of the ITU G.164 standard for echo cancel. That is why you buy cards with add-on hardware echo cancelers that meet the G.164 standard (Sangoma, Digium). Recently you can also buy add-on software echo cancellation from both Sangoma Digium which meet the G.164 standard but beware it exacts a heavy toll on your CPU. But depending on call volume and hardware it might work just fine for you. All of this is a long winded way of saying; you can tune your phone settings until your blue in the face but you won't get rid of the echo. Sorry. So to prove my theory conduct the following tests: Polycom -- Polycom (no echo) Polycom -- Cell phone (no echo) (cell phones do extensive echo cancel) Polycom -- Longdistance (no echo) (telcos do echo cancel on LD) Polycom -- wireline residential (echo!!) That is why your customer reports intermittent echo problems. Hope the above helps you out. John On Fri, 2007-07-13 at 12:51 -0400, Bill Sandiford wrote: Intermittently, both have the echo. They have other other sets in the office not experiencing the echo problem. Their PSTN connection has been properly tuned for echo (via Milliwatt, etc). I'm just looking for a good config for AEC and AES on the Polys (and perhaps gains). By default they are turned off in the stock sip.cfg - Original Message - From: Jim Van Meggelen [EMAIL PROTECTED] To: 'Bill Sandiford' [EMAIL PROTECTED]; asterisk@uc.org Sent: Friday, July 13, 2007 12:30 PM Subject: RE: [on-asterisk] Polycom Echo Problems Couple of things that need to be known: Who has the echo? Your users? or the people who are calling them? How does the system connect to the outside world? (PSTN) Jim -Original Message- From: Bill Sandiford [mailto:[EMAIL PROTECTED] Sent: July 13, 2007 12:23 PM To: asterisk@uc.org Subject: [on-asterisk] Polycom Echo Problems Hi All: I'm having a problem with a customer that has a bunch of Polcom 501 and 601 sets. They are complaining about echo. Does anyone have some suggestions for some good settings for AEC and AES in sip.cfg for the Polys? Any other suggested settings or changes to the stock sip.cfg? Thanks, Bill Sandiford Telnet Communications 905-674-2000 x100 [EMAIL PROTECTED] IMPORTANT NOTICE: This message is intended only for the use of the individual or entity to which it is addressed, and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by email and delete the message. Thank you. No virus found in this incoming
Re: [on-asterisk] Polycom Echo Problems
In the first two scenarios you describe, you are essentially doing pure SIP to SIP using the Polycoms and that should not cause echo unless echo cancel is disabled on the far end handset. I just now re-read your original posting and indeed you have AEC turned off so that is definitely your problem. One thing to try is to ask the far end to put the phone on mute and see if the echo goes away. If it does, then your echo is being caused by acoustic echo, not an impedance miss-match or other network problem. If you narrow it down to acoustic echo (which is actually the only possibility) then the responsibility of eliminating that echo is squarely with the handset (Polycom) and you'll have to try tuning the related settings. We don't use Polycoms but their conference phones have a reputation for very good echo cancel so I'd be surprised if their handsets weren't equally as good. Mind you I just had a look at their spec sheets and they don't claim G.164 so maybe they don't? If you mute the far end and you still get echo then something else very strange is going on. Like your Asterisk is actually looping the call through the PRI or its traversing an analog circuit or some other thing that shouldn't be happening. In the final scenario (SIP Trunk to carrier), you can't do anything since you don't control the Carrier - PSTN where the echo cancel needs to happen. Your carrier should have their own echo cancel so If they are running asterisk with PRI interface cards that don't have echo cancel they you should consider changing carriers. Also have a look at this which gives a pretty good explanation of what causes echo. http://en.wikipedia.org/wiki/Echo_cancellation But bottom line; turn on AEC on the handsets and the problem will go away. Regards, John On Fri, 2007-07-13 at 17:24 -0400, Bill Sandiford wrote: John: Thanks for the description, it is very good. Here is the scenario in which this customer is experiencing echo. Polycom --- Asterisk --- Internet --- Polycom also Polycom --- Asterisk --- IX Private Line (delay 10ms) --- Polycom also Polycom --- Asterisk SIP Trunk to carrier --- Carrier's CLASS 5 --- PSTN This particular customer is seeing echo in all three scenarios. Hence the reason I'm looking into the AEC and AES features of the Polycom. Bill - Original Message - From: John Lange [EMAIL PROTECTED] To: asterisk@uc.org Cc: [EMAIL PROTECTED] Sent: Friday, July 13, 2007 4:38 PM Subject: Re: [on-asterisk] Polycom Echo Problems Echo *always* comes from the far end point. The amount a given person perceives the echo is determined by how loud and how delayed the echo is. Volume and delay are influenced by a number of factors along the call path. Echo is a very complex issue but I'll try and give a brief explanation. In the situation where you have a Polycom phone connected to an Asterisk server which is in turn connected to the PSTN talking to a residential wireline customer, e.g.: Polycom -- Asterisk -- PRI -- Wireline Handset If the Polycom customer hears echo it's coming from the wireline handset (and/or the hybrid but I'm trying to keep this example simple). Most consumer handsets just don't care about generating echo because its never been a problem. So echo is normal on all local wireline calls but you don't perceive (hear) echo because the echo is not delayed. Now when you throw Asterisk in the mix the act of encoding and decoding the voice adds delay. This added delay causes you to perceive echo even though the volume of the echo is roughly the same. Technically, to solve echo you fix the endpoint that's causing the echo. But since you can't replace every wireline phone ever made and the telco certainly isn't going to help you that isn't a practical solution. The best you can do is put an echo canceler as close as you can to the endpoint and in this case it's on the Asterisk box. Unfortunately Asterisk's standard built in echo cancelers are crap. They don't even come close to reaching the level of the ITU G.164 standard for echo cancel. That is why you buy cards with add-on hardware echo cancelers that meet the G.164 standard (Sangoma, Digium). Recently you can also buy add-on software echo cancellation from both Sangoma Digium which meet the G.164 standard but beware it exacts a heavy toll on your CPU. But depending on call volume and hardware it might work just fine for you. All of this is a long winded way of saying; you can tune your phone settings until your blue in the face but you won't get rid of the echo. Sorry. So to prove my theory conduct the following tests: Polycom -- Polycom (no echo) Polycom -- Cell phone (no echo) (cell phones do extensive echo cancel) Polycom -- Longdistance (no echo) (telcos do echo cancel on LD) Polycom -- wireline residential (echo!!) That is why your customer reports intermittent echo problems
Re: [on-asterisk] Polycom Echo Problems
John: Once again, thank you. Your response was again very detailed and helpful. Since my last post (~30 minutes ago), I was able to solve the problems with the third scenario (PSTN). Turned out the carrier had the echo cans turned off for this client on their SIP trunking. Carrier turned on the echo cans and the echo was gone. However, there is still echo in the first 2 scenarios which were both all SIP/VoIP (no PSTN). Its essentially this: Polycom --- Asterisk --- Polycom I tried your suggestion of having the far end mute and you are correct. I am on site and when I place a call I have near-end echo (I hear myself). When the far side mutes, the echo is gone. When the far side unmutes the echo is back. I have turned on the AEC and AES in the Polycom sip.cfg but it hasn't had much of an impact. There are some other settings to do with AEC and AES in the file and hence I am still looking for some recommended settings from anyone that has used them. Regards, Bill - Original Message - From: John Lange [EMAIL PROTECTED] To: Bill Sandiford [EMAIL PROTECTED] Cc: asterisk@uc.org Sent: Friday, July 13, 2007 5:55 PM Subject: Re: [on-asterisk] Polycom Echo Problems In the first two scenarios you describe, you are essentially doing pure SIP to SIP using the Polycoms and that should not cause echo unless echo cancel is disabled on the far end handset. I just now re-read your original posting and indeed you have AEC turned off so that is definitely your problem. One thing to try is to ask the far end to put the phone on mute and see if the echo goes away. If it does, then your echo is being caused by acoustic echo, not an impedance miss-match or other network problem. If you narrow it down to acoustic echo (which is actually the only possibility) then the responsibility of eliminating that echo is squarely with the handset (Polycom) and you'll have to try tuning the related settings. We don't use Polycoms but their conference phones have a reputation for very good echo cancel so I'd be surprised if their handsets weren't equally as good. Mind you I just had a look at their spec sheets and they don't claim G.164 so maybe they don't? If you mute the far end and you still get echo then something else very strange is going on. Like your Asterisk is actually looping the call through the PRI or its traversing an analog circuit or some other thing that shouldn't be happening. In the final scenario (SIP Trunk to carrier), you can't do anything since you don't control the Carrier - PSTN where the echo cancel needs to happen. Your carrier should have their own echo cancel so If they are running asterisk with PRI interface cards that don't have echo cancel they you should consider changing carriers. Also have a look at this which gives a pretty good explanation of what causes echo. http://en.wikipedia.org/wiki/Echo_cancellation But bottom line; turn on AEC on the handsets and the problem will go away. Regards, John On Fri, 2007-07-13 at 17:24 -0400, Bill Sandiford wrote: John: Thanks for the description, it is very good. Here is the scenario in which this customer is experiencing echo. Polycom --- Asterisk --- Internet --- Polycom also Polycom --- Asterisk --- IX Private Line (delay 10ms) --- Polycom also Polycom --- Asterisk SIP Trunk to carrier --- Carrier's CLASS 5 --- PSTN This particular customer is seeing echo in all three scenarios. Hence the reason I'm looking into the AEC and AES features of the Polycom. Bill - Original Message - From: John Lange [EMAIL PROTECTED] To: asterisk@uc.org Cc: [EMAIL PROTECTED] Sent: Friday, July 13, 2007 4:38 PM Subject: Re: [on-asterisk] Polycom Echo Problems Echo *always* comes from the far end point. The amount a given person perceives the echo is determined by how loud and how delayed the echo is. Volume and delay are influenced by a number of factors along the call path. Echo is a very complex issue but I'll try and give a brief explanation. In the situation where you have a Polycom phone connected to an Asterisk server which is in turn connected to the PSTN talking to a residential wireline customer, e.g.: Polycom -- Asterisk -- PRI -- Wireline Handset If the Polycom customer hears echo it's coming from the wireline handset (and/or the hybrid but I'm trying to keep this example simple). Most consumer handsets just don't care about generating echo because its never been a problem. So echo is normal on all local wireline calls but you don't perceive (hear) echo because the echo is not delayed. Now when you throw Asterisk in the mix the act of encoding and decoding the voice adds delay. This added delay causes you to perceive echo even though the volume of the echo is roughly the same. Technically, to solve echo you fix the endpoint that's causing the echo. But since you can't replace every wireline phone ever made and the telco certainly isn't going to help you
