AASTRA DT292 for BusinessPhone User Guide EN - Manual (Page 28)

Outgoing Calls
BusinessPhone – Cordless phone DT292 28
Intrusion
You can intrude on an ongoing call on a busy extension (if this
function is allowed). 8
Press to intrude
Intrusion tone is heard and a three-party call is established.
When the called extension replaces the handset and you keep off
hook, the called extension will be recalled automatically.
Note: If you still hear the busy tone, then your extension
does not have the authority to intrude or the desired
extension is protected against Intrusion.
The number for intrusion may differ from country to country,
see table “ Alternative programming for Automatic Callback,
Camp-on, Intrusion ” on page 84 .