Call Dropouts due to no Comfort noise

[Vin]

Hi All,
long time reviewer, first time poster..

We've setup a fusionPBX (4.2.2) instance, with built in extensions for one context, as well as multiple other contexts to serve as pbx's for some of our clients who run Skype (i've walked in to a non-supported environment - i know )

our skype customers function fine for inbound/outbound calls to all networks, except for one. one of the networks (Vodafone) drops the call if there is silence for 15-30seconds.

the settings i've checked include:
- Sip Profiles:
- VAD enabled 'both'
- send_silence_when_idle - True True
- suppress-CNG (enabled = true, value= False)

the 'Suppress CNG' in the gateway is also set to 'False'

am i missing a setting somewhere? when i go to the CDR's, im not sure what specifically i look for, however i find that "rtp_audio_out_cng_packet_count" always shows '0'

our SIP provider has mentioned that they see the PBX indicating codec 13 (comfort noise), however they reflect that they don't detect any comfort noise if, say, we mute the call.

i've attached a copy of the CDR details from a call that got disconnected after 15s mute time (not sure if that helps)

Thanks in advance for any advice - i'm hoping someone might be able to point me to the obvious setting i've overlooked...

 

[DigitalDaz]

I think much better would be a sip trace.

The real question for me is why would the provider cut the call off after 15 seconds of mute, that just doesn't make any sense??

 

[Vin]

cheers,

the SIP provider did a P-Cap, and found that the header being sent included codec 13 (comfort noise), but mentioned that the moment i hit the mute button, the RTP traffic stopped (no comfort noise after this).

Sorry, it's not the provider cutting the call off, it appears to be the telco who owns the destination number (it works fine for all telco's, except Vodafone, though i've confirmed that the CNG traffic isn't being sent for other telcos either). I've engaged Vodafone's engineers to provide me with what sort've traffic they're expecting to see... but you know, telcos...

 

[Vin]

just an update on this: the telco on the other end highlighted that from their end they are not recieving any RTP when the call is on mute. they check for this every 15 seconds, which is why the call ends after a max of 30s

Just wondering if anyone can comment on if the comfort noise can be performed by the pbx, or whether this would need to be done by the Skype server? i've enabled VAD, supress CNG (false) etc, but no avail.

cheers,

 

[DigitalDaz]

When you tried to set supress comfort noise to false did you stop and restart the gateway? The gateway needs restarting after any changes are made.

 

[Vin]

Hi
Thanks - yes, restarted the gateway.
Should the external SIP profile also be configured with the supressCNG and VAD configurations?

 

[Vin]

So a bit of an update on this.
i had a look at some of the other contexts on the pbx which have no issue, and compared the CDR to a call that dropped out.
attached are the findings.
Columns A-B are the variables and values for the call that has no issue
Columns C-D are the variables and values for the call that drops out after 15-30 seconds of silence.

i'm particularly interested in the 'Sip_Allow" variable setting for each, and wondering if anyone can comment as to whether this could be the cause, and where this variable would be set? (having trouble finding documentation on this)

 

[Vin]

Resolved by adding the following Channel Variables:

"bridge_generate_comfort_noise" (True)
"send_silence_when_idle" (True)

note: i had stupidly come across, and tried this in the SIP profiles, however this doesn't work. Channel Variables is where it's at.