Cisco AS5350 GW Full Duplex vs Half Duplex Conversation

[VoIPgirl]

Hi,
Has anyone ever had an issue with "double talking"? For example, if you call an automated message and try to speak during it, it mutes the automated message until you stop talking. I have disabled vad and also tried disabling echo cancellation. Any suggestions?

 

[MarkHolloway]

I had this problem with Cisco AS5400 gateways and Polycom SoundPoint IP phones. What kind of IP Phones are you using? The problem was related to the Center Clipper and Automatic Gain Control settings. I had to make adjustments to my Polycom global configuration file for the SoundPoint IP phones.

Here is one example of a voice port setting on the AS5400. Make sure your gain is set appropriately.

voice-port 1/0:1
input gain -3
output attenuation 3
echo-cancel coverage 64
no vad


I connect my AS5400's CT3 module as PRI's to a Nortel DMS.

 

[VoIPgirl]

Thank you. This you set in your AS5400. We will try this. We have been changing the IOS and DSP etc with no luck. We are using Cisco 7940 and 7960.

 

[VoIPgirl]

I tried to input the settings you noted and it did not make a difference. I also tried preferencing 711ulaw. I already have it set to no vad. Any other suggestions?

 

[whykap]

It could also be a phone load issue. try upgrading the phone load on the 7960/7940's.

 

[VoIPgirl]

Thank You. We are having this issue on two different phone loads. We have isolated this to the GW. 5.3(0) and 7.2(2.0). What IOS and DSP are you running? What phone version are you using?

If I send the same call over SIP or On-Net, I do not have the problem.

 

[MarkHolloway]

Can you provide a test phone number that I can call? If this is happening when you call an Auto Attendant on the PSTN, I can use that number for testing.

My 7940/7960 phones are running SIP 8.6 firmware. Are you SCCP or SIP firmware? My SIPDefault.cnf has the following:

# Configurable VAD option
enable_vad: 0 ; VAD setting 0-disable (Default), 1-enable

 

[VoIPgirl]

We are running SCCP. No Vad within the AS5400. I think that the settings of the input gain and output attenuation may be what we need, but different numbers. Do I need to adjust it according to the ERL? Here are some stats from the sh port voice log.

Tx/Rx Power : -83.4/-83.4 dBm
Tx/Rx Talker Level : -6.0/-6.0 dBm
Average VAD Background noise level : -120.8 dBm
Average ERL level : 127.0 dB
Average ACOM level : 127.0 dB
Tx/Rx current activity : silence/silence
Tx/Rx byte count : 12160/0
Average ECAN Background noise level: -120.8 dBm