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da at urbanlandcontrac...
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 Posted: Thu Jul 30, 2009 8:37 am Post subject: [Freeswitch-users] voip-voip echo cancel possible |
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We have a carrier that we receive calls from over SIP. They are getting
the call from the PSTN and then sending to us as sip. We then get other
calls to our FS via sip from other carriers that are also from the PSTN.
We bridge these calls in FS. All connections to FS are sip. So.
Party1--PSTN--Carrier1--FS--Carrier2--PSTN-party2
Problem is that Party2 hears echo of themselves. We chased it down and
Carrier1 says it is because Party1's carrier is setting a bit in the ss7
connection that they are doing echo cancel (when in fact, they are not).
So Carrier1 does not do any EC on the call before passing it to us.
Is there any way that I could do the EC on this call in FS?
| Quote: | From what I have read on the list, it looks like the Zaptel Hardware or
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OSLEC type of EC would not work here since there is no zaptel/t1
connection involved with FS.
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brian at freeswitch.org
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| Posted: Thu Jul 30, 2009 8:47 am Post subject: [Freeswitch-users] voip-voip echo cancel possible |
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On Jul 30, 2009, at 8:27 AM, DA wrote:
| Quote: |
We have a carrier that we receive calls from over SIP. They are
getting
the call from the PSTN and then sending to us as sip. We then get
other
calls to our FS via sip from other carriers that are also from the
PSTN.
We bridge these calls in FS. All connections to FS are sip. So.
Party1--PSTN--Carrier1--FS--Carrier2--PSTN-party2
Problem is that Party2 hears echo of themselves. We chased it down
and
Carrier1 says it is because Party1's carrier is setting a bit in the
ss7
connection that they are doing echo cancel (when in fact, they are
not).
So Carrier1 does not do any EC on the call before passing it to us.
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I would take it up with the carrier since that is the point where the
echo is introduced.
| Quote: |
Is there any way that I could do the EC on this call in FS?
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Nope.
| Quote: |
| Quote: | From what I have read on the list, it looks like the Zaptel
Hardware or
|
OSLEC type of EC would not work here since there is no zaptel/t1
connection involved with FS.
|
Only on TDM, You do not need EC on VOIP to VOIP calls.
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frank at impactfax.com
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| Posted: Thu Jul 30, 2009 9:39 am Post subject: [Freeswitch-users] voip-voip echo cancel possible |
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We may have seen this also once before.
But in this case, it is 'needed' (or would be helpful) because the telco
is not doing the EC correctly.
I can see how the originating telco should be the one to fix the
problem. But it always seems that is easier said than done.
Is there no way at all to cancel echo when FS is only in the voip media
stream like this?
-----Original Message-----
From: freeswitch-users-bounces@lists.freeswitch.org
[mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of
Brian West
| Quote: |
| Quote: | From what I have read on the list, it looks like the Zaptel
Hardware or
|
OSLEC type of EC would not work here since there is no zaptel/t1
connection involved with FS.
|
Only on TDM, You do not need EC on VOIP to VOIP calls.
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brian at freeswitch.org
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| Posted: Thu Jul 30, 2009 9:47 am Post subject: [Freeswitch-users] voip-voip echo cancel possible |
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Its not technically feasible to do so its also resource intensive for
something that you shouldn't have to be dealing with in the first
place. Take a cluebat and beat your telco if they don't fix it.
/b
On Jul 30, 2009, at 9:26 AM, Frank @ Impact wrote:
| Quote: | We may have seen this also once before.
But in this case, it is 'needed' (or would be helpful) because the
telco
is not doing the EC correctly.
I can see how the originating telco should be the one to fix the
problem. But it always seems that is easier said than done.
Is there no way at all to cancel echo when FS is only in the voip
media
stream like this?
|
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kristian.kielhofner at...
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steveu at coppice.org
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| Posted: Thu Jul 30, 2009 11:14 am Post subject: [Freeswitch-users] voip-voip echo cancel possible |
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Kristian Kielhofner wrote:
| Quote: | While it might not be feasible it may be possible (and I don't see why not).
There are many, many commercial devices that claim to do this. Then
again there are just as many devices that claim to do everything and
anything...
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People tell me commercial offerings claim to do this, but nobody ever
points me at an example.
There are two key issues that stop EC over VoIP working.
1. There is no way you will ever get EC to work over a low bit rate
codec. Even if you use nothing but G.711 on your local hop, you have no
idea what transcoding may occur downstream. So, in the general case it
won't work however you configure your setup.
2. EC is an adaptive process, requiring is a stable loop length. As soon
as a jitter buffer somewhere makes an adjustment the EC's tunning will
blow up. If you are lucky it might eventually retune, but in the
meantime the pain in your ear could be quite severe. 
Steve
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