Mitel Echo Frustrations **

[kade33]

Evening All,

Circuit provider and ISP here needing some tips on Mitel systems and Echo Issues.

Customer only gets echo from the two IP phones (5540 & 5312) while all analog stations utilizing the same trunks do not have any problem. This happens on inbound and outbound calls on the only two IP sets on location.

Our group has tested call qualities and also backbone quality with no indicators of any issues.

So the real problem at hand.... the vendor onsite will not relay any information to us other than "fix your problems" it is not on my end.

Without the help of the vendor onsite we are of course quickly exhausting any way out of this.

Thoughts?

 

[YnotPhone]

- Is the system type an SX200 ICP?
- Are the IP Phones on the same network as their computers or are there VLANs involved?
- Do the IP sets when calling each other get echo?
- Are all the trunks analog on site?
- What type of switch are they running, or is it coming off the Mitel?

 

[paterson]

Your analog trunks and analog phones do not need any conversion of signal to work. IP phone to analog trunk does need conversion. This conversion is provided by E2T resources (E=ethernet 2=to T=TDM). If the TDM (analog) is working, than the problem is with the IP side or the conversion process. You really have not provided much information to fully help. Hopefully, this may point you in the right direction to look.

One thing that I would be trying to determine first is what the ECHO is.

Is it truly an echo of signal? (Maybe the ear piece of the handset is too loud and the mic end of the handset is picking up the signal and "retransmitting" what is already heard)
Missing pieces of the conversation? (missing data packets means a network issue)
A hollow/tinny quality to the audio? (Bad handset?)

_______________________________________________________________

If you did not take enough time to get it right the first time...

What makes you think that you have time to fix it?

 

[kade33]

Thanks for the tips on what to drill down to. Witout the system vendors support its making it a little difficult to help from our side being the provider.

 

[IrwinMFletcher]

To echo (pardon the pun) what paterson said, you first need to understand what echo is, and why you only hear it in certain scenarios.

Within the systems there is what is called a 'hybrid', essentially a circuit that connects the external 2-wire interface to the internal 4-wire. When that happens, the outgoing signal running on the 4 wire doesn't completely get sent out the 2 wire interface. The signal that gets reflected back down the 4 wire interface is the echo. To use an analogy, think of a 4sq inch hose, coupled to a 2sq inch hose. Even if you only send down 2sq inches worth of water down the larger hose, depending on the characteristics of the coupler (the hybrid), not all of the water necessarily will go into the smaller hose, some may 'splash' back.

It's important to note that this ALWAYS happens. The difference is that when you are talking from an analog phone, the reflection comes back so fast that it appears as side-tone to the user. i.e. the user just thinks it's hearing their own voice as it's speaking. When you're talking from an IP phone, everything is the same in terms of the hybrid and the echo, the difference is that there is extra delay in the conversion from TDM to IP, the network traversal, decoding, etc, that increases the time between when you spoke the words until the echo is played back, so you notice it.

For this reason, TDM trunk providers will often ignore the problem, stating that the system itself is causing the problem, not the lines. It's good enough for TDM, it's only because you're converting it to IP and adding delay that it's a problem. This trend is (or should be) changing as they recognize the use of IP and the trunk requirements of it.

Having said all that, there is the Line Measurement Tool that can be run on the systems to characterize the LS trunks (assuming that this is what you have). You should look at that as a start.

 

[kade33]

- Is the system type an SX200 ICP?
Yes

- Are the IP Phones on the same network as their computers or are there VLANs involved?
LAN based only internally in the SX200

- Do the IP sets when calling each other get echo?
No

- Are all the trunks analog on site?

Yes
- What type of switch are they running, or is it coming off the Mitel?

All based off the sx200

Just spoke again with the vendor and he is still stating it is QOS settings off of our backbone.

 

[IrwinMFletcher]

Have you run the LMT? If so, what were the results? If not, do it and it will qualify the lines from the system perspective.

 

[slapin]

It is definitely not QoS. Nice and clean echo, when you can hear every spoken work back is definitely caused by hybrid interface and its impedance mismatch with the line. Sometimes you will not be able to compensate it with the LMT. I have one site with one sick analog line which is not possible to switch to another pair due to capacity issues in the cable and telco is ignoring my requests. I use Echo Stopper from Mike Sandman. Probably it is not the best solution, but a quick hack which worked for me. To make things worse the impedance is fluctuating and once in a while "trained" people on site tweak the device

Plus echo cancellation module is recommended.