Page for details about call logging.
Calls are logged in the devices placed call log (directories->Place Calls) when a call initially connects to another device. Subsequent changes in the device (eg forwarded) are not reflected in the log.
If a call is not placed to a channel they will not be recorded in the log. eg a call to voicemail will not be recorded. You can force these to be recorded by including progress(), then ringing() in the dialplan.
Example (This will produce a logged call):
Example (This will not):