On busy
If "Call forwarding on busy" is configured on the phone, another incoming call during an active call is not signalled. The call is forwarded to the entered call forwarding destination. Even if call waiting (with or without audible indication) is configured on the phone, another incoming call during an active call is not signalled.
Configuration
Web interface:
Telephony > Call forwarding > On busy
*Details about the settings are in Call forwarding
Phone:
Settings > Telephony > Call forwarding > On busy
*Details about the settings are in Telephony
Provisioning:
*You will find general details about provisioning and how to provision this function in Auerswald DokuWiki