Nortel Meridian 1 Succession 1000M Installation And Configuration Manual page 353

Connecting the telephones Page 353 of 562
If the extension number is already in use by another telephone, you hear
the special dial tone. If the telephone has a display it shows "MULTI-LINE,
EXTENSION?".
To accept the default extension number press the pound key.
To select a new extension number, manually enter an extension number
and press the pound key.
OR
If the extension number is not available for use, the character display
shows "ERROR, EXTENSION?" and you hear overflow tone.
This happens when you choose an extension number manually or when
extension numbers are entered for additional keys. A default extension
number will not be offered if it is not available.
You must repeat step 3 and manually enter a new extension number.
Note 1: If other keys require secondary extension numbers, you are
prompted until you enter all of the required extension numbers for the
model.
Note 2: These extension numbers cannot be defaulted. The text display
prompting for further extension numbers is "KEY kk EXT?" where "kk"
represents the key number requiring the extension number.
Note 3: Each prompt for another extension number is accompanied by
special dial tone. When you are programming an extension number, the
lamp associated with that number on the telephone is lit.
4 Hang up the telephone receiver.
After approximately 10 seconds, the telephone is configured.
Note: If you replace the handset before completing the prompt
sequence, the installation will automatically fail. This can be useful if you
make an error and want to restart the procedure.
End of Procedure
Small System Installation and Configuration