REMOBS

     The Silver Box, as stated earlier, is a lineman's handset or REMOBS
(Remote Service Observing Systems).  They allow Bell employees and phreakers
to use the system to tap phones.  By using a Silver Box and an ordinary Touch-
Tone phone, one can dial directly into the RECEIVE ONLY portion of any
customer's line (the mouthpiece is disconnected).  Silver Boxes work as
follows:
     Dial the number of a REMOBS unit.  Bell apparently puts them in the 555
information exchange (XXX-555-XXXX).  A tone will then be heard for about two
seconds and then silence.  It is then necessary to key in, with a Touch-Tone,
a 2-5 digit security code, holding down each digit down at least one second.
If the code is not entered within 5-6 seconds, the REMOBS will disconnect, and
must be dialed again.  If the code is properly entered then another tone will
be heard.  Any 7-digit customer number can then be entered (the REMOBS can
only handle certain exchanges which are prewired for it, and usually one
machine can't monitor all of a multi-Central Office locality).
     The REMOBS will then connect up to the customer line.  The phreaker will
hear the low level idle tone.  As the monitored party dials, the phreaker will
hear the number being dialed and the entire conversation!  At no time will the
monitored party be aware that he has been tapped - there are no messages,
clicks, strange sounds, etc.!  When the phreaker is done listening to Customer
A, he can key in a single "reset digit" (usually the last digit in the access
code), which disconnects him from the monitored line and returns him to the
tone so that he can dial Customer B.  When the phreaker wants to quit, he keys
in a single "disconnect digit," which disconnects him from the last line being
monitored, and disconnects him from REMOBS so that REMOBS can be reset and be
ready for another caller.