sundance-communications.com Forums Telephony Discussion Phone & VoIP Systems Toshiba Telephones & Systems CIX 670 VM button calls another user instead of going to VM?

I suddenly have two phones where users are unable to access their voicemail by hitting the VM button. Instead, the VM button dials another user's extension.

On the screen, it says "Call 5991-5940V" where the first number is user one's extension, and the second number is the extension called if user one hits his VM button.

I've been looking at campon and automatic call back, but neither seems quite the same - but I'm not very familiar with either one. Trying to figure out what's going on, how it happened, and how I prevent it from happening in the future. Any and all suggestions are deeply appreciated.

Here's pic of the screen

Simple and common. Technically this is a message key, not a voicemail key. Someone else turned on this extension's message key.
What is the difference? Well if it was a voicemail key then it would always call the voicemail system. You will notice that this button does nothing while when it is not blinking.
Traditionally a lot of PBX systems have a message key. Another extension can turn on this key to request that the person calls them back. When that person calls back the 1st party, and the original person picks up the phone, then message LED should clear.

The easiest way to clear this is to dial the code #409 on the phone that has the blinking MSG key.

A Toshiba tech could change the settings to prevent this from happening. I disable this feature in every one of my installs if they have a voicemail system, and usually even if they don't.

As Newtecky said 5940 has sent a MW to the handset of 5991 by either dialing 5991 then 7 or 5991 and pressing the MW key
#409 will cancel all MW indications on the handset as there can be many "banked" up on the same handset.
You will also notice if handset 5991 presses the MW key and the call is answered at 5940 then the light would go out (unless there was many MW lights sent from the same extension then you have to reply multiple times until they are all answered)

That handset also has a call forward external set on it as well.
If you need to cancel the CF External dial #6051

This is very helpful, thank you both.

What setting should be changed to prevent this from happening again?

If it is a digital station - Program 200 FB 41 Activate Message Waiting - set to disable
If it is an IP station - Program 260 FB 37 Activate Message Waiting - set to disable.

Thank you!

Was going to suggest the same but ToshiGal75 beat me to it