Date/Time Group settings not effective on IP Phone

UCM Version:  7.1.3.20000-2

IP Phone: 7942, 7965 with firmware version 8.5.2SR1

Normally if you want different phones to display time in different timezone, you can create multiple Date/Time Group and then apply to the respective Device Pool on UC Manager.  I’ve found it is not working on my UC Manager.  I tried to change the time zone from GMT to

(GMT+8:00) Asia/Hong_Hong

It doesn’t work.  The phone still shows the GMT timezone.  Other settings like I’ve change the Separator to “-“ dash, the changes is effective on the phone, only the timezone is not working.  After some research I’ve found that my phone load 8.5.2SR1 or even the latest 8.5.3, only support the timezone with the “*” entry.  In my case, change it to

(GMT+8:00) Australia/Perth*

and it works like a charm!