This requires CLI....
nano /etc/asterisk/voicemail.conf
Add needed timezone under:
[zonemessages] eastern=America/New_York|'vm-received' Q 'digits/at' IMp central=America/Chicago|'vm-received' Q 'digits/at' IMp central24=America/Chicago|'vm-received' q 'digits/at' H N 'hours' military=Zulu|'vm-received' q 'digits/at' H N 'hours' 'phonetic/z_p' european=Europe/Copenhagen|'vm-received' a d b 'digits/at' HM pacific=America/Vancouver|'vm-received' Q 'digits/at' IMp central=America/Vancouver|'vm-received' Q 'digits/at' IMp
In FreePBX Under "Voicemail Options" add the following:
tz=pacific
Now Reboot Server and test
https://community.freepbx.org/t/voicemail-timezone-configuration/1933/7