Case A
- virgin (unconfigured) device is booting. It asks DHCP server for configuration. Not mentioning others, it request NTP server and time offset options. DHCP server respond to such request. Phone got time from NTP server and display them. Unfortunatelly, it uses no time offset obtained from DHCP server as is. For some unknown reason, it apply th eoffset but then eigth hours is subtracted from it. For example
Current time (from NTP server): 13:00 GMT
Time-zone delivered by DHCP: 7200 second
Time expected to be shown: 15:00
Time shown on display: 7:00
Well, it's not so important problem, unprovisioned phone is short-term temporary state. I'm just curious I missed something important or the phone's logic is just broken and DHCP-delivered offset can't be used for anything usefull.
Case B
Fully provisioned phone. There are several options affecting the time with unclear interactions between them (yes, I read pages 192 and 193 of Administrators guide).
Both NTP and PBX supply the same time, 20:00 GMT.
Time Zone is set to GMT+0100
Time Offset is not set (empty).
Ignore DHCP Time Offset is set to NO
Daylight Saving Time Enable is set to YES, Daylight Saving Time Rule is set to start=3/-1/7/2;end=10/-1/7/2;save=1 (e.g. DST is in effect today)
DHCP delivered time-zone is 7200 seconds
Phone show 23:00 on display.
If Ignore DHCP Time Offset is set to YES then 22:00 become shown on display.
I understand the "YES" case - 20:00 GMT, one hour is added because of GMT+0100 Time Zone, another hour is added because DST is in effect. DHCP time-zone is ignored because of configuration, local Time Offset is not set at all. So 22:00
But I really don't know how 23:00 has been calculated in "NO" case.
Is there someone who know more about it ? Thank you.
