Abstract: A computer having a modem is programmed with software (also called a “on-hook/off-hook detector”) that detects a change in status (e.g., on-hook or off-hook) of a device (e.g., a telephone having a handset) by measuring a change in the signal power of a signal flowing through a telephone line connecting the modem and the device. In particular, the computer programmed with the on-hook/off-hook detector detects a status of a telephone handset by measuring power of a reference signal and measuring power of an instantaneous signal on the connection and comparing these two measurements. The reference signal is a constant signal whose power does not change. Then, the computer programmed with the on-hook/off-hook detector is able to detect whether there has been a change in status of the telephone handset by comparing the detected status with a previous status of the telephone handset.