| 摘要 |
PURPOSE:To allow all telephone sets in a group to sound and to make an effective telephone call by giving plural extension telephone set a common group telephone number, and allowing all telephone sets in the same group to sound when the group number is dialed. CONSTITUTION:Extension telephone sets A-N connected to an automatic exchange are grouped and groups 1 and 2 are given characteristic group telephone numbers. A signaling circuit 4 has a circuit with generates different signal tones for group calling and individual calling respectively and a control part 7 decides on whether a calling dial number received from a calling telephone set corresponds to the individual calling or group calling. In case of the group calling, a group ring-back tone is sent to all telphone sets in the group. In some of telephone sets in the group answers, the generation of the group ring-back tone is stopped and a talk loop to the calling telephone set is formed. |
