> Generally, these kind of attacks work like this: a person trying to
> break in dials up the modem, and then simulates a hangup noise and
> dialtone WITHOUT ACTUALLY HANGING UP. The dialback modem thinks the
> line has hung up, picks up the line, dials, and waits for a carrier.
> The person supplies a carrier, and viola, connects to the system.
Well, that's just *broken*. Either that, or it's from the way-back days
when the callee couldn't hang up on a call if the caller stayed off
hook. Nowadays, there's no possible reason why a callback modem wouldn't
just hang up the line itself before picking up, listening for dial-tone,
The other means of breaking into a callback modem is to have the phone
company add call forwarding to the employee's phone (who checks?), have it
forwarded to the cracker's modem, and then call in. --Darren