Facsimile terminal equipment having communication speed switch

In a system for communicating data between first and second facsimile terminal equipment units through a communication circuit such as an ISDN circuit, the first facsimile terminal equipment unit comprising:

• a communication processing portion having transmission and reception means for transmitting and receiving data at a communication speed between the first and second facsimile terminal equipment units and for transmitting and receiving at least one of a plurality of predetermined flag patterns each of which represents a respective data communication speed to be used;
• receiving condition judging means for determining whether the transmission and reception means receives the data successfully by determining whether the flag pattern received by the first facsimile terminal equipment unit is the same flag pattern which was sent to the second facsimile terminal equipment unit, or by determining whether the flag pattern received by the first facsimile terminal equipment unit can be read;
• speed switching instruction means for providing a communication speed switching instruction when the transmission and reception means does not recognize the flag pattern;
• and
• speed switching control means for switching the communication speed of the transmission and reception means responsive to the communication speed switching instruction provided by said speed switching instruction means.