Warm Dial is a feature (since firmware version 10.1.26.0) that initiates an automatic call to a pre-configured number if no other number is dialled after a configured time out (e.g. fifteen seconds) once the phone goes off hook.
// Any value smaller or equal to 2 will trigger a Hot Dial if auto_dial_taregt is set. Any value larger than 3 will switch the behavior to Warm Dial <auto_dial perm="">15</auto_dial> // A target has to be set otherwise the regular auto dial behavior will trigger <auto_dial_target perm="">+4922157634433</auto_dial_target>
You can set the destination and time period on the WUI: