Ericsson DT190 User Manual page 26

Outgoing Calls
26
Intrusion
You can intrude on an ongoing call on a busy extension (if this
8
function is allowed).
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
Camp-on,
"Alternative programming for Automatic Callback,
Intrusion" on page 78.
BusinessPhone – Cordless phone DT190