Patent ID: 7738652

Claim:
A method for preventing a modem from blocking a telephone line, the method comprising: establishing, by modem circuitry and modem software of the modem, a communication across the telephone line with a remote modem; servicing, by the modem, the communication across the telephone line with the remote modem; and detecting, by the modem circuitry of the modem, that the modem software has become nonfunctional with respect to the communication by: writing transmit data and an on-hook command to memory wherein each time the modem software writes transmit data, the modem software overwrites a previously written on-hook command with transmit data and writes a new on-hook command immediately following currently written transmit data; determining that the modem software has become nonfunctional when the modem circuitry reads the on-hook command from memory; and releasing, by the modem circuitry, the telephone line when it determines that the modem software has become nonfunctional with respect to the communication.