BCM 50 Echo on Analogue Lines 1

[cobac]

I also have a bad echo problem with a BCM50 with analogue lines.

The digital phones work fine, outbound calls sound great.

The problem is with the IP phones I am testing.

i2004 (4)
NTDU92BA70
Firmware: 0604D4B

I have taken the entire LAN portion out of the equation. The phone is plugged directly into a LAN port on the BCM50. I have the phone hard coded to 100Full. I have tried new patch cables, different phones, etc.

Internal calls sound OK. (No echo at all)

I have also set the codec to G.711-ulaw and the jitter to Auto. Echo cancellation is enabled in the media gateways section.

Changing the codec from Auto to G.711 helped a bit, callers say I sound "clearer" but only I can hear a consistent echo when I talk.

As soon as I connect to one of the analogue ports and get a dial tone, if I start to speak the dial tone dims down until I stop talking. Then it goes back to dial tone. As soon as I connect everything sounds clear until I start talking, then I get to hear myself repeating everything.

Connecting a regular pots phone to the lines has no echo as well as the digital sets which I mentioned.

I have a feeling its something simple I overlooked, but I would appreciate a help in the right direction.

Thank you very much!

 

[inet2xtreme]

Have you adjusted any of the items under "Active Physical Lines" such as the loss package, impedance or trunk mode? I'm not sure if those would help, but my '50 has:

Trunk mode: Supervised
Dial mode: Tone
Loss Package: Medium CO
Impedance: 600
Link at CO not checked.

I too have that same firmware on our i2004 phone sets with no issues. We currently have our 4 lines feeding in through a 4x16 combo media bay module and have not turned up any of the on-board trunk interfaces, but have loaded the keycodes for them.

So far, we have not had any issues with our '50. It is running great. I use the i2004 from that system as my primary office set every day.

 

[cobac]

Yes, those are the same settings I have. I have tried changing the loss package but that does not seem to make any difference.

Also tried "lowering" the receiver volume on the handsets but that didn't make a difference either.

Oh also, the analogue trunks are going into the RJ45 breakout / wallmount kit. But it performed the same even when it was punched down to a block...

Thanks for the info...

 

[inet2xtreme]

Maybe your '50 has old software from the beta days. What version of software is yours? Under system, ID ours has 1.00.2.04.g (North America)

 

[cobac]

Yup, same version here too...

 

[3Sixty]

Has any one asked the network provider to increase the gain of the lines????.

Marshall

http://www.marshallshouse.co.uk

 

[cobac]

No not yet. Do you think that will make a difference? Just curious if the other T series phones are working fine on the unit, just the i series experience the echo.

There are some other aux analogue lines coming into the office, I will try to patch into them and see if they are any better than these 4.

I guess I could always try the Level 2 reset as well?

Thanks

 

[MagnaRGP]

I would suspect the set itself. I have had a similar problem with a 200 and IP sets. Replaced one of the sets wtih my test unit and there was no problem.

Try swapping the handset from an M series phone onto on eof your IP sets.

 

[3Sixty]

Then the problem is not the lines or the module. But a problem with the phones or the network as MAGNARGP has stated. Have you tried plugiing one I series handset on the BCM 50 LAN port with a crossover cable? I would try this and see if you still get the echo.

Marshall

http://www.marshallshouse.co.uk

 

[cobac]

Yes, tried all three phones also plugged into the LAN port and they all have the echo problem.

It comes and goes, usually starts at the beginning of the phone call and will go away for a minute and then come back.

In an intercom call, the "dial tone" appears lower than when I switch to an analogue line. Of course the echo problem only happens on the analogue lines.

I also performed a level 2 reset on Friday and reprogrammed from scratch. Same thing.

The M series handset seemed to have helped a little bit...

Do you think I need to adjust the gain on the analogue lines down? (Lowering the volume on the handset itself doesn't make a difference)... How about any of the telephony resource settings changed from their defaults?

Of course this is the first BCM I am working with, part of me is starting to think this is the way the system is. But, I never had this problem on Cisco/CallManager...

Thank you guys for all the help/responses!

 

[BigJakeG]

I am having the same problem with the bcm50 call me at 270-392-0843 or 270-392-7647. I would like to talk to you about the system and the echo on the phone thanks

Jake Goodwin

 

[AlquestTech]

Here is some basic info about echo and VoIP

Locating an Echo

In Figure 2, Bob experiences the echo problem, which means that a signal is leaking from his transmit path into his receive path. The fact that Bob hears an echo illustrates one of the basic characteristics of echo: Perceived echo most likely indicates a problem at the other end of the call. The problem that is producing the echo that Bob hears, the leakage source, is somewhere on Alice's side of the network (London). If Alice was experiencing echo, the problem would be on Bob's side (Montreal).

The perceived echo leak is most likely in the terminating side of the network for the following reasons:

* Leak-through happens only in analog circuits. Voice traffic in the digital portions of the network does not leak from one path into another.

Analog signals can leak from one path to another—electrically from one wire to another (called crosstalk), or acoustically through the air from a loudspeaker to a microphone. Also, analog signals can be reflected in the hybrid transformer in the tail circuit. (See the section "Effect of Hybrid Transformers on Echo.") When these analog signals have been converted to digital bits, they do not leak.

All digital bits are represented by analog signals at the physical layer and these analog signals are subject to leakage. The analog signals that represent bits can tolerate a good deal of distortion before they become too distorted to be properly decoded. If such distortion occurred in the physical layer of the PSTN, the problem would not be echo. If you had connectivity at all, you would hear digital noise instead of a voice echo.

* Echos arriving after very short delays, about 25 milliseconds (ms), are generally imperceptible because they are masked by the physical and electrical sidetone signal.

This point is a corollary to the previous assertion that echos become increasingly annoying with increasing mouth-to-ear delay. A certain minimum delay is needed for an echo to become perceptible. In almost every telephone device, some of the Tx signal is fed back into the earpiece so that you can hear yourself speaking. This feedback is known as sidetone. The delay between the actual mouth signal and the sidetone signal is negligible, and sidetone is not perceived as an echo.

Also, your skull resonates during speech (an acoustic sidetone source) and the human auditory system has a certain integration period that determines the minimum time difference between events that will be perceived as separate events rather than a single one. Together, these phenomena create a minimum mouth-to-ear delay of about 25 ms before an echo signal can be perceived.

Given these two reasons—that echos must be delayed by at least 25 ms to be audible, and that leaks occur only in the analog portion of the network—you can deduce much about the location of the echo source. Figure 3 shows possible sources of echo in a simple Voice over IP (VoIP) network.


This is from Cisco's site:

http://www.cisco.com/en/US/tech/tk652/tk701/technologies_white_paper09186a00800d6b68.shtml#1054995

But the principles are the same regardless of product.
This should help you locate the source of the problem

I have usually found it to be in the CO or carrier and fixed by padding down the circuits.

 

[ford53]

If this is a analog tro. set up a call on a IP phone and when you have echo. Find the analog line put a butt set on the line and mon. to see if you can hear the echo. If so go off hook with the butt set and open up the line to the BCM. The echo should still be there. Have you checked to see if the echo is always on one line or all? Do you have echo when only one line is in use or a combo of or more?

 

[cobac]

BigJake - Did not see your post from a few weeks ago sorry...

Still having the echo problem yes. Basically switched to using the T series digital sets because the IP phones were just impossible to conduct business on. It was a faint echo, really noticeable when you turn the volume up on the headset.

There are 4 telephone lines, and an additional fax line. I even tried plugging the fax line in (as a 5th voice line) and that echos as well. 2 i2004 phones, 1 i2002 phone... the softphone forget it... Usually using 1 line at a time... the additional lines are for conf calls, etc..

The network interface point from Verizon has pluggable jacks on it, so also tried plugging directly in from those using an RJ11 cable into the breakout kit that you can buy with the BCM50 wall mount.

Doesn't seem to make any difference... really frustrating... Again, plugging an analogue phone into the CO lines is fine...

Going to try borrowing or setting up a different VOIP system and see if this system is just poor or something else...

I did not try the butt set idea, that is a good one...

Did you get anywhere with your problem?

 

[gwramirez]

I'm curious to know if anyone has found a fix for this issue. I too have the same problem on a BCM 200 Rel 3.7.

G.William Ramirez

http://www.gwramirez.co.nr

http://www.ld.net/iptelephony

 

[endlesswinter]

It is probably the i2004 set itself. Have you tried another?

 

[cobac]

I put new i2004 and a new i2002 sets in and it still has the same problem. I'm sure if you just plan on using the digital instead of the IP phones the system is fine.

I put in another VOIP system and there are no problems, so it must be the system or phones.

 

[JasonPM]

cobac,
I noticed that in your first post you mentioned that the phone was hard coded to 100Full. If the system is set to Auto and your phone is 100/full there will be a duplex mismatch. Autonegotiation will only match the speed and duplex if BOTH devices are set to auto otherwise the auto side will default to half.

 

[endlesswinter]

I had a similar problem and doing a full system reset cured the problem.