Call bindings
The call binding function allows calls from specific phone numbers (e.g. calls from the door) to be linked to a camera and up to two function keys. For example, a call binding can be used to open a door or switch on a light.
Video: IP Camera and call bindings 
*Link to video (only in German) https://www.youtube.com/watch?v=8nx44UfFOG8
Configuration
Web interface: 
Telephony > Call bindings
*Details about the settings are in Call bindings
Phone: 
Settings > Telephony > Call bindings
*Details about the settings are in Telephony
Provisioning: 
*Details about provisioning this function in the Auerswald DokuWiki