Default = No. This setting only applies to Server Edition systems.
The system setting to enable the use of Gmail for voicemail.
When set to Yes, you can configure users for Gmail on Call Management > Users > Add/Edit Users > Voicemail.
Upload Google Service account generated keys
You must register the Voicemail Pro application for the Gmail API in the Google Developer’s console. You must create a Google service account and generate the JSON and P12 key files.
Use the JSON Key File and P12 Key File buttons to upload the files to Web Manager. Web Manager transfers the files to the Voicemail Pro application.