In Asterisk in the initiation of the call through the AMI interface if extension is busy (talking), the call doesn't bounce. If on softphone enabled DND mode, or hang up manually(by press red button on softphone), it bounces, as necessary:
-- Called 198
-- SIP/198-00000d90 is busy
Action:Originate
ActionID:1234
Channel:SIP/198
Context:from-internal
Priority:1
Exten:0991112233
Async:false
CallerId:obzvon
Timeout:30000
Asterisk 12.5.0, FreePBX 12.0.7.
Common Freepbx dialplan without customizations.
CallWaiting Disable
Put in "Context: default" - no result.
Sorry for bad english.