| 摘要 |
PURPOSE:To attain talking among three parties such as a telephone call on an external line, a handset and a base unit by releasing the retention of an external line to connect the base unit to an external line when an INTERCOM key is depressed. CONSTITUTION:When the base unit 2 or the handset 1 is talked with the telephone set of the external line, the talking is attained among the three parties of the handset 1, the telephone set of the external line and the base unit. In talking among the telephone set of the external line, the base unit 2 and the handset 1 (three parties), the base unit 2 is necessary to depress the INTERCOM key 253 simply and then depress the INTERCOM key 253 once more when the handset 1 responds, and this is similar in transferring a call from the handset 1 to the base unit 2 and the operation of the talking among the three parties is attained simply. |
