Patent ID: 7352849

Claim:
A short message service switching private branch exchange (PBX) system, comprising: an office line interface unit of the PBX system that interfaces with office lines; a voice mail interface unit of the PBX system including a digital signal processor and a memory, the voice mail interface unit converting a first pulse code modulation format short message service signal transmitted from the office line interface unit into short message service data, and converting the short message service data into a format of a terminal that will receive the short message service data; a control unit of the PBX system that switches a pulse code modulation channel of an office line to which a speech path is coupled into a pulse code modulation channel of the digital signal processor, and determines a type of the terminal that will receive the short message service data; and an extension line interface unit of the PBX system that transmits a short message service signal having the format corresponding to the type of the terminal determined by the control unit, wherein the digital signal processor converts the pulse code modulation format short message service signal transmitted from the office line interface unit into the short message service data by decoding, the digital signal processor converting the short message service data into a second pulse code modulation format short message service signal when the short message service data is to be transmitted to a single line terminal, and the digital signal processor outputs the short message service data as is when the short message service data is to be transmitted to a digital terminal, the memory storing the short message service data, and wherein the control unit determines whether a digital signal processor resource of the digtal signal processor is available when a speech path is connected, the control unit further waits for a prescribed time until the digital signal processor resource of the digital signal processor becomes available when the digital signal processor resource is not available, and finishes a reception of the short message service signal if when the digital signal processor resource becomes available after the prescribed time has elapsed.