[cisco-voip] 2801: VoIP -> PSTN Echo Problems

[Johan Bloemhard]

I have been pulling my hair out concerning echo problems from IP->PSTN
calls.  I have been through the
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a
0080149a1f.shtml website multiple times that Ryan has previously
suggested reading.  

 

It is an intermittent problem so it's very hard to troubleshoot.  I have
a TAC case open but the TAC engineer is having me capture data in the IP
Port and the GW port (extremely difficult to do in a production
environment).  Also the TAC engineer hasn't asked for any info on the
2801 (i.e., sh tech-support) or configs so it's my belief that maybe
it's being looked at from the wrong direction.

 

I was able to get a call out and pull the "sh call active voice" for the
call.

 

IOS: Cisco IOS Software, 2801 Software (C2801-SPSERVICESK9-M), Version
12.4(10), RELEASE SOFTWARE (fc1)

 

My stats for the call are as below which obviously my echo cancellation
isn't being activated.  I find it hard to believe that I can have an
ACOMLevel of 0 but I'm not sure what could be causing this.

NoiseLevel=-62

ACOMLevel=0

OutSignalLevel=-70

InSignalLevel=-65

InfoActivity=1

ERLLevel=0

EchoCancellerMaxReflector=19368 

 

My voice-port configuration is as follows:

Cisco-2801#sh voice port 0/1/1

 

Foreign Exchange Office 0/1/1 Slot is 0, Sub-unit is 1, Port is 1

 Type of VoicePort is FXO

 Operation State is DORMANT

 Administrative State is UP

 The Last Interface Down Failure Cause is Administrative Shutdown

 Noise Regeneration is enabled

 Non Linear Processing is enabled

 Non Linear Mute is disabled

 Non Linear Threshold is -21 dB

 Music On Hold Threshold is Set to -38 dBm

 In Gain is Set to -5 dB

 Out Attenuation is Set to 5 dB

 Echo Cancellation is enabled

 Echo Cancellation NLP mute is disabled

 Echo Cancellation NLP threshold is -21 dB

 Echo Cancel Coverage is set to 64 ms

 Echo Cancel worst case ERL is set to 6 dB

 Playout-delay Mode is set to adaptive

 Playout-delay Nominal is set to 60 ms

 Playout-delay Maximum is set to 250 ms

 Playout-delay Minimum mode is set to default, value 40 ms

 Playout-delay Fax is set to 300 ms

 Connection Mode is plar

 Connection Number is 6331

 Initial Time Out is set to 10 s

 Interdigit Time Out is set to 2 s

 Call Disconnect Time Out is set to 60 s

 Ringing Time Out is set to 180 s

 Wait Release Time Out is set to 30 s

 Companding Type is u-law

 Region Tone is set for US

 

 Analog Info Follows:

 Currently processing none

 Maintenance Mode Set to None (not in mtc mode)

 Number of signaling protocol errors are 0

 Impedance is set to 600r Ohm

 Station name None, Station number None

 

 Caller ID Info Follows:

 Standard BELLCORE

 Caller ID is received after 1 ring(s)

 Translation profile (Incoming):

 Translation profile (Outgoing):

 

 Voice card specific Info Follows:

 Signal Type is loopStart

 Battery-Reversal is enabled

 Number Of Rings is set to 1

 Supervisory Disconnect is signal

 Answer Supervision is inactive

 Hook Status is On Hook

 Ring Detect Status is inactive

 Ring Ground Status is inactive

 Tip Ground Status is inactive

 Dial Out Type is dtmf

 Digit Duration Timing is set to 100 ms

 InterDigit Duration Timing is set to 100 ms

 Pulse Rate Timing is set to 10 pulses/second

 InterDigit Pulse Duration Timing is set to 750 ms

 Percent Break of Pulse is 60 percent

 GuardOut timer is 2000 ms

 Minimum ring duration timer is 125 ms

 Hookflash-in Timing is set to 600 ms

 Hookflash-out Timing is set to 500 ms

 Supervisory Disconnnct Timing is set to 350 ms

 OPX Ring Wait Timing is set to 6000 ms

Cisco-2801#

 

Thanks in advance,

 

Johan Bloemhard 
Senior Information Technology Specialist 
___________________________________ 
Silver Falls School District 4J 
802 Schlador Street 
Silverton, OR 97381 
w: 503.873.6331 

 

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