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How to Evaluate The Voice Quality of ATAs

2007-7-10

Voice Delay

Delay is the time which was spend for a voice signal to travel end-to-end between talker and listener and often manifests itself as an apparent time lag between when the talker speaks and when the listener responds. If too much delay is presented, voice conversations can become impossible.
ITU Recommendation G.114 recommends a maximum of 150 milliseconds for one-way delay for most user applications.

Below is the voice delay test environment graph and result using G.729 of GIX100,
The result was evaluated by Agilent Voice Quality Tester (VQT).

Echo in a telephone environment is usually caused by hybrid wire junctions in a network in which a portion of the energy from a person’s voice signal is reflected back to them on the same line. Echo diminishes the person’s perception of call quality because it makes it more difficult to have a conversation.

This strength of the echo reflection is expressed in terms of Echo Return Loss (ERL):
ERL (dB) = Original Signal Level (dBm) – Echo Signal Level (dBm)
Echo Return Loss Enhancement (ERLE) is defined by G.168 as “The attenuation of the echo signal as it passes through the send path of an echo canceller. This definition specifically excludes any nonlinear processing on the output of the canceller to provide for further attenuation.”
ERLE (dB) = Echo Signal Level (dBm) – Residual Echo Signal Level (dBm)

Testing Voice Quality on Next Generation Networks Using the Agilent VQT
ITU-T G.168
The detailed information of GIX100 please visit http://www.e3call.com
For Voice Quality of GIX100 please send a mail to support@e3call.com