PURPOSE: To improve the line operating efficiency by giving two extension numbers to same extension ports and sending a call signal of 16Hz and 1300Hz.

CONSTITUTION: When a telephone set 5 dials an extension number for telephone set provided to a telephone set integrated facsimile equipment 4, a CPU 7 indexes an extension number terminal number reference storage device 9 based on the dialed extension number to recognize the relevant terminal number corresponding to the dialed extension number and the telephone set integrated facsimile equipment 4 is used as a telephone set. When the facsimile extension number given to the telephone set integrated facsimile equipment 4 is dialed from the facsimile equipment 6, the CPU 7 indexes an extension number-facsimile extension number storage device 10 to recognize which extension telephone number the facsimile extension number corresponds and the telephone set integrated facsimile equipment 4 is used as a facsimile equipment, Thus, the advantages of the telephone set integrated facsimile equipment are sufficiently utilized.