How do I reset a password if I do not know the existing one?

Before you can do anything you need a M7310. Programming a Nortel voice mail requires M7310. It uses the 3 soft keys under the display to program it. You can get one cheap on EBAY. Next you need to find out what type of Voice Mail System in connected to your Nortel phone system. Below is a link to a Older StarTalk manual. You may have a StarTalk, StarTalk Flash, or a Call Pilot.
http://www.myuserguides.com/Nortel_Norstar_Startalk.pdf#page=15&zoom=auto,-69,407

Below is a link that tells how to reset the System Manager Password.
Reset Admin Password Norstar Meridian and Nortel BCM Help Guides

The default code and password for System Admin is F983 and 1020000 or 1021111. The photo below shows a system admin programming tree. Hope this helps
Charlie

Try Feature 808 before pressing the touchtone digit - it tells the Norstar to send Long Tones to the remote system.

A Nortel Key Service Unit, an ICS (MICS,CICS), BCM (50,100 etc), Norstar (308,616,824), an Avaya IP Office running Nortel cards, or there is another company that makes a Nortel emulation key system but I can't recall what it is right now.

Carl

Do you mean Voice Mail?

Have your office manager or on site admin change it or call your local vendor for admin training or cheat sheet.
You can also get required info from any Norstar Setup and Operation Guide

To program a intercom key for your boss. press feature *2, press the button you want to be your bosses button(one of the ones on the lower end of the phone where the LCD screen is), then enter in his intercom number.

Have your system administrator go into voicemail programming and reset the mailbox password. The default password will be "0000".
I hope you understand that having passwords in the first place is a security measure, so I will not give directions for hacking into your companies voicemail system.

The Norstar 616 system was made before CLID was readily available. You could however, purchase a Nortel CICS system with CLID card(s). CI trunk cards handle up to 4 lines per card making the capacity of the system 8 lines by 16 stations.The CICS system will work with the existing m7310 sets you have so you wouldn't have to incur the cost of new telephones.

You need to unplug something, just not the phone.

The two lines are probably conferenced together. Go find the gray Nortel cabinet and pull the plug on it.

Carl

If the extension was a swap of the old M7310 with a new(ish) M7310 no additional programming should be necessary. However if the phone was replaced with another type of nortel set(M7208, M7324,T7313 etc.) then the phone will default to its base features. To re-program the feature keys press feature *3, the button you wish to program, and the feature code for that button

Actually, even as a technician, you will never know the origonal password.
But you can get in to reset the existing password back to 0 0 0 0.

There are a couple of steps; depending on your voicemail system, voicemail's are done differently, but try this first.

got to a M7310 set
-> dial FEATURE 9 8 3
-> password: 1 0 2 0 0 0 0
-> you should now see ADMIN and under that MBOX, AA, OTHR
press MBOX
-> press CHNG
-> dial the extension of the phones that you need changed
-> you should now see PASSWORD and under it RESET, press RESET (This resets the mailbox back to 4- zero's)
-> hit the * to back up and repeat fopr all the other extensions.
-> hit RLS after all is done and voila... you have now changed those passwords to those mailboxes.

Now when the new users dial F981 at their desks, and dial 0 0 0 0 the first prompt they get is pleasde change password.