Improved method and apparatus for detecting an attempted three-way conference call on a remote telephone

摘要

Methods and apparatus for use in connection with a telecommunication between a local telephone and a remote telephone, which are capable of detecting whether one of the parties to the communication has attempted to initiate a three-way, i.e., conference, call by using a hook-flash signal. The apparatus includes a low pass filter for passing energy having frequencies below about 500 Hz, and an energy detector for detecting a specific electrical energy pulse characteristic of the hook-flash having passed through the low pass filter. The existence of the hook-flash is confirmed by digital signal processing equipment which identifies a rapid drop-off in energy also characteristic of the hook-flash signal. Optionally, the hook-flash may be further confirmed by including software for cooperating with the energy detector to ascertain whether sound has occurred in the telecommunication during a predetermined period following the first hook-flash signal.