I believe the user has enabled Selectable Display Messaging.
This is from the "Features" Manual for the SL1100. It would appear it is controlled by a key. Look for a key that is lit, press "Speaker" and the key to cancel the feature. SC751 then 18 will program a key to enable/disable the feature. I copied the relevant pages from the manual to help. ~ Mike
An extension user can select a preprogrammed Selectable Display Message for their extension.
Display Multiline Terminal callers see the selected message when they call the user’s extension.
Selectable Display Messaging provides personalized messaging. For example, an extension user
could select the message GONE FOR THE DAY. Any display Multiline Terminal user calling the
extension may hear a DND signal and then see the message.
Operation
To select a message:
1. Press Speaker key.
2. Dial PRG 11-11-14.
-ORPress
the Text Message key (PRG 15-07 or SC 751: 18) + enter digits to append (if needed) +
press Speaker key to hang up. Skip the remaining steps.
3. Enter message number.
4. + enter digits to append (if needed) + press Speaker key to hang up. Skip the remaining steps.
5. (Optional for messages 1~8 and 10.)
Dial the digits you want to append to the message.
You can append messages 1~8 and 10 with digits (e.g., the time when you will be back). Enter the time
in 24-hour format.
6. Press Speaker key to hang up.
Intercom calls to extensions with Selectable Display Messaging set receive a DND signal and receive
the display message on their telephone display instead of ringing the extension based on the setting in
PRG 20-01-02.
To allow calls to ring through and have the message displayed on the calling extension display, cancel
DND by pressing DND key + dialing 0.
To cancel a message:
1. Press Speaker key and the Text Message key (PRG 15-07 or SC 751: 18).
2. Press Speaker key to hang up.
Using the Text Message Service Code to select a message:
1. Press Speaker key and dial the Text Message service code (PRG 11-11-14).
2. Dial the Selectable Display Message number to be used (01~20).
(Optional messages 1~8, and 10, dial the digits you want to append to the message.)
3. Press Speaker key to hang up.