How can i improve echo?

[Halea]

Anybody out there has tackled the echo problem? I downloaded and read the famous "Cisco" document regarding echo on phone lines. It's very interesting but it doesn't help much.
I have GXP-2000 phones, BT-102 phones, and professional quality analog phones connected over SPA-3102 and HT-488 to 3CX. I have currently 5 different VOIP services, two from Euorope and 3 from the US. My local network is connected to the WAN over redundant high speed connections of two different types with both professional class Cisco routers. My PSTN lines are from two separate phone companies.
In any combination you can possibly imagine, I have echo problems which range from average to severe while I have 3CX in the loop. When I take my phones and configure them to go straight to my VOIP providers' lines without going through 3CX, or when I connect my analog phones to the gateways in bridge mode without going through 3CX the echo level is almost always inexistant, or very slight (in the worst case scenario)! Even my GXP-2000 phones which arguably is echo prone according to articles that I found on the net give me CD like quality (you get my point) when I connect it to InPhonex directly.
I understand that 3CX doesn't massage any signal, but just connects a data stream from one point to another. So, how come that my echo problems are so bad and show up in any combination of hardware as described above?! My 3CX computer is an older but brand-name high quality piece of hardware.
I am rather puzzled. Frankly, my setup is decent to run experiments and hold casual talks with friends, but not acceptable for corporate or professional level use.
Those who are selling these things to enterprises out there, could you comment on your (or customers') level of satisfaction with this issue? Thanks.
3CX fellows out there: any suggestions about how to address this issue?
Halea

 

[SY]

Re: Echo problems continue...

Yes, there is a suggestion. You can investigate this problem more carefully, and publish any reclamation related to following assertion:
"3CX PBX is not a source of echo"

Thanks a lot for your information

 

[Halea]

Re: Echo problems continue...

Very useful comment! keep up the good work!

 

[SY]

Re: Echo problems continue...

Very useful comment! keep up the good work!

Halea,

Sorry, I forgot to add "smiles"...

On this forum you can find few threads related to such problem.

3CX PBX is not a source of echo, as result it cannot compensate it. Echo can be caused by a lot of reasons. Each device should compensate its own reasons.
Why it happens... It completely different story...
I could ask you to send me WireShark capture of PBX host traffic for a case of "call with echo" (it is to analyze RTP streams), but I don't want to bother you with such request.

Thanks for your comments

 

[N_G]

Re: Echo problems continue...

If you want to reduce echo problems, use professional VOIP equipment: Patton gateways, SNOM phones, you will hear the difference immediately.

The routers are really not very important in this matter (of course they should support static port mapping). So having CISCO routers but cheap VOIP equipment wont really get you the results you want.
Also keep in mind that if you want to use VOIP providers you must have a good quality internet connection.

 

[h2009]

Re: Echo problems continue...

So when you say quality equipment, things link linksys dont really count, but are the benefits of getting say SNOM phones really that noticeable?

Its ashame SNOM dont make wireless kits for there phones, like linksys do

 

[N_G]

Re: Echo problems continue...

Linksys phones work fine. Linksys 3102 can be made to work well but you need to know it very well.

SNOM make a wireless DECT phone, the M3

 

[mandev]

The Smon 360 and 3102 are equally as good if the 3102 is tuned correctly and has a good handset on it, if not disaster.

Jitter buffer size and impedance really cause echo as do cheap dect phones. Amazing what a headset does on a DECR Uniden.

3CX does'nt cause echo but it sure can make it 10 times worse if you do something silly.

You will notice that calling from SMON to SNOM locally should be perfect but as you add delay from remote networks things get worse.

Study the tech manual and avoid the UDP packets going through the media server if you can and make sure there is no codec translation you WILL hear that for sure. Also study what the media server is doing, the more work the more delay. Avoid using 2003 or VM ware, it adds delay and you CAN hear it.

Is anything else running?

In these forums you see people saying Linux based PBX's sound better, thats not true. But it is true that the code path thru windows can bey longer and echo delay gets magnified and that makes things worse.

So stop the echo at the source, in the phone and 3102, reduce or elimite media server delay, make all codecs teh same.

 

[SY]

The Smon 360 and 3102 are equally as good if the 3102 is tuned correctly and has a good handset on it, if not disaster.

Jitter buffer size and impedance really cause echo as do cheap dect phones. Amazing what a headset does on a DECR Uniden.

3CX does'nt cause echo but it sure can make it 10 times worse if you do something silly.

You will notice that calling from SMON to SNOM locally should be perfect but as you add delay from remote networks things get worse.

Study the tech manual and avoid the UDP packets going through the media server if you can and make sure there is no codec translation you WILL hear that for sure. Also study what the media server is doing, the more work the more delay. Avoid using 2003 or VM ware, it adds delay and you CAN hear it.

Is anything else running?

In these forums you see people saying Linux based PBX's sound better, thats not true. But it is true that the code path thru windows can bey longer and echo delay gets magnified and that makes things worse.

So stop the echo at the source, in the phone and 3102, reduce or elimite media server delay, make all codecs teh same.

In general, it is a question of quality of echo cancellation implemented in device. Sure we should find a way to support it (echo cancellation) for the cases if it will be really necessary or there are no other ways to do it.
I had received few reports about "loud echo" with complete set of network traffic captures. It is funny, but original streams didn't contain any echo (almost no echo to be honest).

I still cannot find answer why echo was loud in those cases...

Thanks a lot for your information