| 摘要 |
PURPOSE:To enable an external incoming call to be informed even during the extension talking by providing an extension line between base units and supplying a display signal of external incoming line. CONSTITUTION:An extension line I is provided between the base units B1 and B2 and a signal from a bell tone generating circuit 13 is fed to the extension line I. Thus, for example, the base unit B1 is called from a handset H1, connected to the base unit B2 through the extension line I, and the base unit B2 calls, e.g., the handset H2 to attain extension talking. Moreover, if a call comes to an external line E1 during the talking of the extension line, a signal from the bell tone generating circuit 13 is fed to the extension line I, sent to the handsets H1, H2 to attain the notice of incoming call. Thus, in hooking on the handsets H1, H2 in this state, the talking with the external line E1 is attained from an optional handset (H1-H3). |
