[Freeswitch-users] False Answer Supervision (FAS) - Question

[Vlasis Hatzistavrou (KTI)]

Hello Alfredo,


On 12/4/10 8:23 μμ, Alfredo Quiroga-Villamil wrote:
> Thanks for the response Vlasis. We run statistical analysis for FAS in
> our production routes.
>
> This request would be for a controlled environment where I am using
> GrandStreams 488 to convert from Voip to PSTN. I was thinking that
> perhaps FS has a way to allow me somehow access to the Signaling
> portion of the protocol. If that was the case, I would be able to hack
> my way around it and perhaps ignore the first 200 I receive and not
> propagate it to the origination gateway. This is the setup I am
> looking at:
>
>    

Are you absolutely certain that when your carrier (or test rig) gives 
FAS you receive two 200 messages instead of one? Have you verified it 
using Wireshark captures?

> A =>  B =>  GrandStream Device =>  PSTN
>
>     SIP   SIP
>
> A/B - Both Gateways
>
> This is a test environment I am using, something I am just playing
> with. So in every case I will receive a FAS from the GrandStream
> device.
>
> Do you know if there is a way to launch an application from the
> DialPlan and have access to intercept Signaling; something that would
> allow me to see the messages coming in and make decisions based on
> them like propagate or do not propagate that message. I know this is a
> tough thing since I am literally asking for access to the SIP Stack.
>
>    

Perhaps there is a way to create an app to detect when a SIP 200 message 
arrives, but I still have reservations whether 2 such messages arrive... 
I'd like to help you in this, so, do you have a packet capture file to 
share where 2 200 SIP messaes are sent?

Regards,
Vlasis.