Sony Ericsson Dialog 4223 - Manual (Page 26)

Outgoing Calls
BusinessPhone – Dialog 4223 Professional / Dialog 3213 26
Busy extension
You call an extension and receive busy tone.
Camp-on
You can notify a busy extension of your call by a muted ringing call.
camp-on Press (see display).
Keep the handset off hook. When the called extension replaces the
handset, it will be called automatically.
Note: If you receive the busy tone again, the desired
extension does not allow Camp-on.
Intrusion
You can intrude on an ongoing call on a busy extension (if this
function is allowed).
intrusion Press (see display).
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, your extension does
not have the authority to intrude or the desired extension is
protected against Intrusion.