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 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.