Silent knight 005205 Dialer Module Has the function to seize the telephone lines and activate a trouble-alert if a line failure is sustained for 45 seconds or longer. Plugs in to the Model SK-5204 board Compatible with all major reporting formats including SIA (security industry standard), SK FSK(4/2), SK4+2 tone burst, SK 3/1, SESCOA 3/1 and Radionics BFSK.