Using Tests And Diagnostic Tools; Identifying The Source Of Echo - Mitel MiVoice Business Voice Quality And Troubleshooting Manual

USING TESTS AND DIAGNOSTIC TOOLS

If necessary, you can use the tests and diagnostic tools described in this section to collect
additional data on specific voice quality issues.

IDENTIFYING THE SOURCE OF ECHO

It is normal to receive reflection on a call from the PSTN to a phone on the MiVoice Business
system.
• If the echo delay looking into the PSTN, measured at the demarcation point, is short (< 50
ms), then the PSTN and CPE at the other end of the connection are not responsible for
canceling the echo. In this case Mitel equipment must cancel the echo from the PSTN, to
prevent the echo from being heard by the IP phones. Without cancellation, the IP phones
would hear echo because of the delay over the IP connection. If the delay between the
demarcation point and phone is short, which would be the case if a Mitel analog phone is
used, then there is no need for Mitel equipment to cancel the echo.
• If the echo delay looking into the PSTN, measured at the demarcation point, is long (> 50
ms), then the cause is likely the long delay audio path on the customer premise equipment
on the other side of the PSTN. In this case, the customer premise equipment is responsible
for removing the reflection from the long delay path before it enters the PSTN (short delay
path).
If a MiVoice IP Phone is experiencing echo on an external call, you can identify the source of
echo by placing a call from a Mitel analog phone to the same external destination:
• If you hear echo, the customer premise equipment on the other side of the PSTN is the
source. The echo must be corrected in the CPE on the other side of the PSTN.
• If you do not hear echo when you call from a Mitel analog phone, the MiVoice Business
equipment is likely the source and the echo must be corrected in the Mitel equipment.
Figure 10 illustrates these two possibilities:
Figure 10: Identifying the Source of Echo
Using Tests and Diagnostic Tools
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