[VoiceOps] Help Identifying Strange Tone

[David Knell]

Best guess - it's fake ringback being generated by some auto fax/voice
switch.

--Dave

On Wed, Jun 22, 2016 at 5:37 PM, Justin Grow <jgrow at flowroute.com> wrote:

> This is an interesting one. I'm running into issues with a fax application
> for a few numbers that are playing back a strange tone I have yet to
> identify. I originally thought it was FAS with international ringback, but
> it's occurring on a variety of numbers on various networks.  The tone is
> playing immediately upon answer. Any help identifying what is causing this
> tone or what it is intended for is appreciated.
>
> The numbers are all fax lines and do get the proper CED after this tone. I
> can't find any matching tone in the T.30 ITU-T rec. As best I can figure,
> it's 400Hz with a 0.03s period on/off cycle, played 1s on 2s off. Listen at
> the below link. Sorry for the compression; email me and I can send you the
> original wav recording.
>
> https://clyp.it/vcq010th
>
>
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>


-- 

David Knell, Director, TelNG
T: +44 1223 797979 / +1 970-315-4721
W: http://www.telng.com
H: http://www.daveknell.com
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