U.S. Robotics 4000 Line Sharing Device. USR CALL DIRECTOR LINE SHARING ROUTE VOICE/FAX CALLS ON ONE LINE LINSHR. 1 x 3 - Manual - Fax Machine, Modem, Telephone US Robotics U.S. Robotics USR4000 4000 Line Sharing Device - 1 x Phone Lines - 3 x Devices - Manual