Abstract: A personal computer includes a PBX control program and one or more switch cards located in expansion board slots. The one or more switch cards are coupled to one or more port expansion units (PEU), which are coupled to telecommunication lines out to the various extension phones at the customer premises. Each PEU contains its own digital signal processor (DSP) so that distributed digital signal processing may be implemented to avoid any bottlenecks. One master PEU is coupled to a switch card by a time division multiplexed (TDMA) bus as well as a packet switched control bus, and all the other PEUs, if any, are coupled to the master PEU by extensions of the TDMA and packet switched buses. The TDMA bus carries PBX real time conversations while the packet switched bus carries control information, voicemail outbound message data packets, and inbound voicemail data packets.

Abstract: A PBX system using an unmodified personal computer as the host server and using expansion slots to couple one or more switch cards to the system bus, and, optionally including a network interface card to couple the PBX system to other client computers running telephony enabled applications to control the PBX via a local area network. The switch card(s) are each coupled to a chain of one or more port expansion units that do not consume expansion slots. Each PEU contains a DSP and a microcontroller, an FPGA and port interface circuitry to interface to POTS CO lines, extension telephone lines, T1 lines or PRI lines. The personal computer is programmed with a PBX process that controls operations of the overall system and may also be programmed with conventional voice mail applications or integrated voice response and other applications to implement various telephony functions such as recording voice mail or prompt callers to input DTMF tones indicating what they want to do.

Abstract: A PBX system using an unmodified personal computer as the host server and using expansion slots to couple one or more switch cards to the system bus, and, optionally including a network interface card to couple the PBX system to other client computers running telephony enabled applications to control the PBX via a local area network. The switch card(s) are each coupled to a chain of one or more port expansion units that do not consume expansion slots. Each PEU contains a DSP and a microcontroller, an FPGA and port interface circuitry to interface to POTS CO lines, extension telephone lines, T1 lines or PRI lines. The personal computer is programmed with a PBX process that controls operations of the overall system and may also be programmed with conventional voice mail applications or integrated voice response and other applications to implement various telephony functions such as recording voice mail or prompt callers to input DTMF tones indicating what they want to do.