Hello TREG'ers,

I'm trying to get a handle on the number of FAX machines that do not generate
the 1100 Hz calling tone.  Can anyone enlighten me or vector me to a resource?

Calling tone is the method used by most FAX/telephone switches to detect if
an incoming call is a FAX call or a voice call, but some FAX machines don't
produce them, in part because the T.30 standard doesn't (or didn't) require
this tone.  I believe there was an effort to make this a requirement, but
I'm not sure if this came to be or not.

I've heard anecdotally that about 5% of the existing FAX machines today do
not produce calling tone, but I have no way to confirm this number.

Any info?

  -- Scott Roleson

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 Scott Roleson, PE              |   Internet: [email protected]
 EMC & Telecom Engineer         |     http://www.WP.com/SRoleson
 San Diego Division  MS 8-60    |   Telephone: +1-619-655-4809
 Hewlett-Packard Company        |   FAX:       +1-619-655-5931
 16399 W. Bernardo Drive        |   Amateur Radio:  KC7CJ
 San Diego, CA  92127-1899  USA |   Any opinions are my own, not HP's.
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