I need to silence an extension on the lucent 18d telephone

Programming can be done from either extensions 10 or 11.

If your changing the speed dial numbers under the individual buttons thats done by pressing feature 00, the button you want to change the speed dial number on, and enter in the new number.
If your changing the system wide speed dial numbers, From extension 10 enter in feature 00, press feature then the 3 digit code for the speed dial bank (600-699), then enter in the new telephone number. Either press feature and the next 3 digit code for the next number or press feature 00 if finished.

Intercom 777
enter admin extension (0)
enter password (1234)
Option 3

Hello.
To listen to your messages
Press Intercom 777
At the prompt enter your extension number (Feature 00 before starting the procedure will tell you your extension number)
At the prompt enter your passworde (1234 is the default)
Listen for the instructions

Cheers

From the phone at extension 10 or 11 press FEATURE 00 Left Intercom Left Intercom #103 and enter the 4 digit military time. (if you need it, the date is #101 in mmddyy format).

Press FEATURE to exit

Carl

Press intercom * extension number to page directly

AT EXTENSION 10 OR 11:

FEATURE 00
LEFT INTERCOM TWICE
#103
ENTER TIME AS 4 DIGITS, 24 HOUR MILITARY FORMAT
FEATURE 00

Are you talking when calls come in on the main number or calls going to an extension?

Are you trying to change if it rings or how it sounds when it rings?

The phone you have (Partner 18D) can be used on several different Avaya phone systems that all program differently. To change when it rings, this would need to done in the system programming (not the phone) All the manuals are avaialble on Avaya's web site but you need to know which system you have before you can start searching. www.avaya.com