Depends to some degree on how that other voicemail connects to the system but you didn't say.

If is analog extensions, put then in a group, turn off the Message Button Goes to Visual Voice settings. Set the Voicemail Type to Group and set that group as the destination.

Otherwise, I would look at the 46xxsettings file the system is passing to the phones to see if the voicemail server address is somewhere in there (I know the conference server address is). If so, add a 46xxspecials.txt file with that address changed to whatever might work.

I say 'might' as its all guessing.

Stuck in a never ending cycle of file copying.

The 3rd party Voicemail server links to IPO via SIP extensions. To retrieve the message, we dial to Pilot number of this SIP extension group and the call is routed to 3rd party Voicemail.
I'm looking for the way to assign this pilot number to the Message button of the phone.

So try the Group option and see what happens!

Stuck in a never ending cycle of file copying.

@sizbut,
You mean the Group setting on Phone or on Manager?
According to 46xxsettings.txt sample of Avaya, use the "SET PSTN_VM_NUM XXX" to modify the message key.
I tried modify the 46xxsettings.txt with either "SET PSTN_VM_NUM XXX" or "SET SET MSGNUM XXX" but also not work.


But press to "message key" still shown the default

Read my original reply, replacing the word "analog" with "SIP".

Stuck in a never ending cycle of file copying.

...and don't edit the 46xxsettings.txt file, let the system auto-generate that from its configuration and share it with the phones (if you really have to, put any changes you really want in a 46xxspecials.txt file). The IP Office will also tell the phones what the voicemail settings are.

So in the System | Voicemail settings, turn off the Message Button Goes to Visual Voice setting. Set the Voicemail Type to Group, and set the Voicemail Destination to your group of SIP extensions that are connected to the 3rd-party voicemail system.

Stuck in a never ending cycle of file copying.

@sizbut,
- This is Server Edition. In System - Voicemail - Voice Mail Type only 2 options: Voicemail Lite/Pro & External Over SM Line. No option "Group".

- The phone access directly to Avaya Voicemail if disable the "Message Button to Virtual Voice"
- I changed the 46xxspecials.txt also but no changed