Device to block unauthorized modem access over a PBX line
 A modem detector that enables detection of whether a modem is coupled to a phone line. When one is detected, various responses can occur, including: hanging up on the modem; checking if the modem linkage is allowable and, if it is not, then hanging up on the modem; and/or logging in the occurrence of an unauthorized modem access. To provide protection against unauthorized modem access, a digital embodiment can be used at the T1 phone line or an analog embodiment can be used after digital telephone data is converted into analog signals. 
Hewlett-Packard Company
H
H04M
inventional
Hans Richard C.
von Braun Walker