PURPOSE: To eliminate malfunction due to a manual switching by automatically transmitting a communicated data stop setting request signal as a call request to a connection destination when a handset is picked up to attain an originating state and switching to a telephone set from a data terminal equipment.

CONSTITUTION: If the handset of the telephone set 1 is picked up in the middle of originating data, a control circuit 6 detects whether an hook switch 11 is hooked off or not with the aid of a hook state detection means 62. The control circuit 6 asks a communication control means 61 whether data is transmitted or not. If a stop is feasible, the circuit 6 interrupts the data transmission, and informs an operator of the effect. The control circuit 6 checks that no data is transmitted, and transmits the data communication stop getting request signal to a telecommunication line 7 from a stop setting request signal transmission means 65. When the connection destination data communication control equipment of the telecommunication line 7 interrupts the data transmission with the aid of the stop setting request signal, the control circuit 6 knows that the communication control means 61 stops data reception. A reception signal identification means 68 receives a stop acceptance signal. Due to the stop of reception, the control circuit 6 instructs a switch drive means 64, switches and connects the connection destination of the telecommunication line 7 from the data communication equipment to the telephone set 1, and forms a channel.