1. A computer-based telephony system, comprising: a telephone set which implements telephony functions on a telephone line, said telephone set including a serial interface for bi-directional communication of data signals including data signals generated in response to user input to said telephone set; and a computer executable software application running on a computer connected to said telephone set via said interface for receiving first ones of said data signals from said telephone set generated in response to user input to said telephone set and in response implementing predetermined software functions on said computer, for transmitting further data signals from said computer to said telephone set in response to a user input to said computer whereupon said telephone set implements predetermined ones of said telephony functions, and for generating and displaying on said computer a window including an area for indicating telephone call status responsive to one of either said user input or receipt of said first ones of said data signals, wherein said window includes a status line having icons for indicating said predetermined ones of said telephony functions which have been implemented by said telephone set.