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Network Connectivity - Is my VPMADT032 installed and operational?

Network Connectivity - Is my VPMADT032 installed and operational?

    Table of Contents

    PROBLEM:

    How can I determine whether my hardware echo canceler (VPM) is functioning correctly?

    RESOLUTION:

    1. After the DAHDI drivers have been loaded, execute the following command on the Linux shell to check if the VPMADT032 is installed and operational.

    dmesg|grep VPMADT032

    The following is an example of the output you should see.

    VPMADT032 Loading firmware... Success

    Booting VPMADT032

    VPMADT032: Present and operational (Firmware version 125)

    Note that the version of firmware reported will vary depending on the version of DAHDI installed.

    Also note that the VPM will take precedence over any software echo cancelers configured in /etc/dahdi/system.conf, so if the VPM firmware loads correctly Asterisk will use it over the software echo cancelers.

    1. Once you've verified that the VPM firmware loaded successfully, check '/etc/asterisk/chan_dahdi.conf' for the 'echocancel' line.  To enable the VPM, this setting must be "yes" or some numerical value.  "yes" corresponds to 128 taps, and the numerical value can be any power of two:  32, 64, 128, 256, 512, or 1024 (latter is maximum allowable value).  So either of these lines is acceptable:

    echocancel=yes

    echocancel=1024

    1. The 'echocancel' parameter must be declared before the 'channel' parameter in order to turn on echo cancellation for those channels. You can determine if echo cancellation is enabled for a given DAHDI channel by issuing the following command in the Asterisk CLI:

    dahdi show channel 1

    1. Change the '1' in the command above to the channel number you wish to examine.  You should see a line in that output similar to this:

    Echo Cancellation: 128 taps, currently OFF

    Note that echo cancellation will only show as ON when a call is currently active on that channel.  The number of taps can be used to verify that it is enabled instead. The number of taps reported for a given channel should match the value of the echocancel parameter (or 128 if specified as yes). If the number of taps is reported as 0 or 1, then echocancellation is not enabled.