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VG cable-detect

John Vosburg

I have implemented voice-port cable-detect on my VG350 (15.3(2)T) with SM-D-72FXS modules and MGCP signalling loop start.  The documentation is not specific as to what is defines "connected" and "not connected" state and  I have a functioning phone that shows "not connected" state.

How exactly does the DSP detect connected? 



4 Replies 4

Rob Huffman
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Hall of Fame Community Legend

Hi John,

If you shut/no shut the port that shows up as disconnected

does it reflect "connected" in the status?



"May your heart always be joyful
And may your song always be sung
May you stay forever young " 

- Dylan

Hi Rob,

I could do that and see if it clears the condition.  But I am primarily interested in technically what line condition or test the DSP does to determine connected/not connected.



Hi John,

Only syslog messages are displayed as a notification for change in cable detect status. There won't be any change reflected in the output of the show voice port summary.

Use the following configuration to see the change in cable detect output

  voice service pots


Use "show voice cable-status all" command to see the cable status.

Refer to following link to get more info on cable-detect-poll-timer and information on show command to analyze cable detect

Refer to following link to get moe info on show commands for cable status

Thanks & Regards,
Mudit Mathur

Thanks & Regards, Mudit Mathur

John Vosburg

Found out from the TME:

The VG350 performs cable-detection by using low-voltage REN measurement. This means the FXS port will inject a low ring voltage into the line and measure the impedance. If the impedance is low (means there is a ring circuit) the assumption is that there is a phone plugged in.

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