Re: Comparison of THC-SCAN v2.0 with Sandstorm PhoneSweep 1.02

[oxymoron () WASTE ORG (Oliver Xymoron)]

On Thu, 31 Dec 1998, Adam Maloney wrote:

> If memory serves me (which it normally does) my old USR sportster (and
> probably the couriers) have a VOICE result code.  It's trivial for the modem
> to figure out if it has connected to another modem or if there's some
> "yelling idiot" on the other end.

And if you have a modem with voice support (or are willing to shell out
less than $100 for one), you can do this right. Voice modems are capable
of sending and receiving samples and can be configured to send out-of-band
messages indicating different types of carriers, DTMF, multiple types of
busy signals, silence, etc. All this with AT commands and a bit of escape
code processing.

Better yet, free code already exists to drive several popular models of
voice modems in the form of mgetty+vgetty, and it provides a scripting
interface with several examples. It would be relatively easy to create a
Perl or shell script to dial, detect fax/modem/other, save a sample of the
greeting, and then run signal processing tools on the greeting to identify
it. I haven't looked at the waveforms, but I suspect it would be
relatively easy to distinguish the typical VMB/answering machine from live
voice as phone recordings have a pretty low cutoff frequency. Not to
mention detecting telco greeting tones, etc. Multiple lines, DB access,
and all sorts of other amazing features are also relatively trivial.

And those with access to ISDN (eg ISDN-for-Linux) or PRI interfaces could
of course do the sampling even more conveniently..

Now that I've mentioned voice modems, I'll also mention that the ones I've
looked at can send/detect all four DTMF columns and have a lovely command
for generating single- or dual-tones of arbitrary duration and
frequencies. Does it strike anyone else as funny that they're
shrinkwrapped?

--
 "Love the dolphins," she advised him. "Write by W.A.S.T.E.."