Mitel 5550 User Manual page 77

Unable to Setup or Add to Conference
Either:
there is a restriction in your COS/COR preventing you from
setting up a conference;
you have reached the maximum number of trunks allowed in
a conference;
you have reached the maximum number of conferees allowed
in a conference; or
you cannot have two attendants in a conference.
Unassigned Directory Number
The number you dialed is not recognized by the telephone
system. Verify your number and try again.
Wake-up Call Not Acknowledged
Part of the Hotel/Motel Feature package. The guest has not
answered the automatic wake-up. (Note: The Hotel/Motel
package is an optional feature.)
Wake-up Call - System Error
Part of the Hotel/Motel Feature package. The Wake-up function
is not operating properly. Contact your communications
department.
You are already using the selected language. Language not
changed.
You made a mistake in selecting the language. Repeat the
procedure.
Reference 69