Can you post your config?
You might be missing the time-zone command under CME.
UC540#
UC540#config t
UC540(config)#telephony-service
UC540(config-telephony)#time-zone ?
<1-53> select timezone name used by IP phones (offset in minutes)
1 Dateline Standard Time -720
2 Samoa Standard Time -660
3 Hawaiian Standard Time -600
4 Alaskan Standard/Daylight Time -540
5 Pacific Standard/Daylight Time -480
6 Mountain Standard/Daylight Time -420
7 US Mountain Standard Time -420
8 Central Standard/Daylight Time -360
9 Mexico Standard/Daylight Time -360
10 Canada Central Standard Time -360
11 SA Pacific Standard Time -300
12 Eastern Standard/Daylight Time -300
13 US Eastern Standard Time -300
14 Atlantic Standard/Daylight Time -240