PBX with configurable analog CO line and T1 signalling protocols using packet bus and software switched WAV channels

An apparatus comprising:

• a personal computer having a plurality of expansion slots;
• one or more switch card circuits coupled to said expansion slots, each including a switching integrated circuit capable of coupling data in at least one timeslot to at least one other timeslot on a time division multiplexed bus and further comprising an interface circuit for a time division multiplexed bus and a packet switched bus;
• one or more port expansion units coupled together in a daisy chain by a time division multiplexed bus and a packet switched bus, each said daisy chain of port expansion units having a port expansion unit in the chain coupled to a switch card via a time division multiplexed bus and a packet switched bus which are extension of the packet switched and time division multiplexed buses which couple each daisy chain together and a bus interface circuit for said buses, each port expansion unit including one or more port interface circuits for interfacing the port expansion unit to a central office plain old telephone service line or a T1 or PRI ISDN line or an extension telephone, and each port expansion unit including one or more digital signal processors coupled between said bus interface circuit and said port interface circuits and one or more microcontrollers coupled between said bus interface circuit and said one or more digital signal processors;
• and wherein said personal computer is programmed with a PBX program to control said host computer to implement a PBX process that communicates with said microcontrollers on all of said port expansion interface circuits to determine call progress and port status and sends data to said microcontrollers to control signaling functions implemented by said port interface circuits and to control switching of said switch cards to implement at least some conventional PBX functionality;
• and wherein said microcontrollers in each port expansion unit are programmed to read status signals from said port interface circuits and report said status to said PBX process and to receive commands from said PBX process and send commands to said port interface circuits to implement signaling functions and to write tone data to a digital signal processor in said port expansion unit to cause tone generation on channels designated in data received from said PBX process for signaling purposes;
• and wherein said one or more digital signal processors in said port expansion unit are programmed to receive data from said time division multiplexed bus for channels corresponding to PBX connections that are already made or which are to be made and said tone data and programmed to implement a volume control weighting function to mix said channel data and said tone data and send the resulting data to the appropriate port interface circuits representing each incoming signaling tone and decode said data to determine which tone has been received and for interrupting said microcontroller for each said tone received;
• and wherein said one or more microcontrollers are programmed to respond to each interrupt from said one or more digital signal processors and determine the tone which has been received and send a message to said PBX process identifying the tone which has been received.