Functions > Call Waiting > Call Waiting Signalling via Tone

Call Waiting Signalling via Tone
Incoming calls during a call are indicated by a change in the display.
If call waiting signalling via tone is enabled, incoming calls during a call are also indicated by a tone on the receiver.
 
Proceed as follows:
Using COMfortel Set (page Settings/functions > Signalling/ringer, check box call waiting (tone))
Using the telephone (menu settings > signalling > attention tone)

COMfortel 1400 - Firmware V2.2 - COMfortel Set V3.16 - Advanced Information V07 02/2019