[Freeswitch-users] FAS detection with FS

[Anthony Minessale]

you could use the existing tone_detect app after the false answer to xfer to
an extension of your choice if ring tone was detected.


2010/1/8 Ahmed Naji <a.alalousi at gmail.com>

> Hi Valsis,
>
> Thanks for this.
>
> My line of thought is to tone-detect secondary ringing tones post 200(OK)
> to detect FAS (False Answer Supervision). This should eliminate at least a
> good proportion of calls, and it can be done real time through a
> script/modules/...etc.
>
> Working along this thought, at least you are minimising the hit cost-wise
> to a few seconds at most.
>
> As to answering machines and fake conferences, fake network messages
> ...etc, one can possibly use voice detection, perhaps with heuristic and
> statistical training.
>
> Just a thought ..
>
> Regards,
>
> Ahmed.
>
>
> 2010/1/8 Vlasis Hatzistavrou (KTI) <vhatz at kinetix.gr>
>
>  Hello Ahmed,
>>
>> I don't think there is a reliable way to detect FAS on a per call basis.
>> Even audio detection software can be confused by strange ringtones,
>> answering machines, etc.
>>
>> The most reliable way we have found is to use statistics from CDRs and see
>> if the INVITE-to-200(OK) delay averaged over a number of calls appears to be
>> too small. If it is, then it is possible that you got FAS for those calls.
>>
>> But this can only tell you if you have been experiencing FAS in past
>> calls, ie you will not know you are getting FAS in real time.
>>
>> It is still useful however: after you detect a possible FAS case via
>> statistics you can place a few test calls yourself to verify that there
>> actually exists FAS (and this is the only information that a carrier will
>> accept in a trouble ticket to prove to them that they actually give you
>> FAS).
>>
>> I hope this helps.
>>
>> Best regards,
>> Vlasis Hatzistavrou.
>>
>>
>> On 8/1/10 3:05 πμ, Ahmed Naji wrote:
>>
>> Hi everyone,
>>
>> Was just wondering what/if anyone is doing any work on FAS detection and
>> spoofed ring tones. Be great to discuss some ideas.
>>
>> Regards,
>>
>> Ahmed.
>>
>> --
>> Ahmed Naji
>>
>>
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>
>
> --
> Ahmed Naji
>
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-- 
Anthony Minessale II

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