Login/Logout No Voicemail Password

I’m sure that I am just missing the setting somewhere but I can’t find the No Voicemail Password option for Yealink phones.
The EMP user guide/wiki says under global Astra settings:
No Voicemail Password- This is the password used to login or logout a phone if the extension does not have a voicemail box, since the default is to use the voicemail password.

But there are no Yealink global settings.
Is it related to: ML-API (RestAPI) Default Login?
That field is only an enabled/disabled field, what does it do?
Current EPM version: