jump to navigation

VoIP Troubleshooting 101 – Diagnosis & resolving Echo Issues March 22, 2010

Posted by TelUS Consulting Services in VoIP catagory.

When you try to resolve echo problems, consider the following items:

Determine whether this echo occurs while using a handset, a headset, or a speaker phone. If  it occurs while using a headset, the type of headset is important, as well as whether the headset port on the IP Phone is being used or whether an external amplifier is connected to the handset. The impedance switch on a headset transformer can cause echo problems.

Echo cancellation is a function of remote end of a given connection. That is, if the call is terminated at another IP Phone, the remote IP Phone performs the echo cancellation for the caller. If the call goes through the MRP to the central office (CO), both the DSP in the MRP and the CO contribute to echo cancellation. The echo cancellation range on the MRP voice port may need to be tuned if a CO is involved. For T1 ports, using 16-ms echo cancellation is appropriate. For analog ports, 32-ms echo cancellation can be used.

When FXO ports on the MRP are used, the input gain may need to be adjusted, although a large volume increase can contribute to echo. If the input gain needed adjusting and was set to greater than 0, try bringing the input gain back down to 0 (default). You will need to do shut/no shut on the voice ports after you make each change. If this does not help at all, try to increase the output attenuation by 2 dB or so, to see whether that improves the situation.

our next installment of VoIP Troubleshooting 101 will be a discussion of one way audio

Joe Buck, N.C.E.

%d bloggers like this: