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Hi. Sounds a strange one, I've had a look through Nokia's forums and it seems more like a one-off than anything (not widely reported). With Vodafone providing the network and SIM side and Nokia responsible for the hardware itself (the phone) itself it might be worth reporting on their forum.
Vodafone customer since 2004. Attempting to help where I can on the Community
I remember having this sort of issue years ago when I had a Nokia 5800 xpress Phone.
I used to turn the Phone off at night as the Alarm function would still wake the Phone (and me :smileywink: ) But when the clocks went back or forward it wouldn't change until later in the day!
Did you have the Phone On or Off? I'm just thinking if the Phone was Off, it might not have syncd to the Network Server in order to update the time?
Slightly odd one there. Is there a setting for "Get time from service provider", and is it ticked? I have an old (Android) device with no SIM that resolutely displays GMT if I allow it to auto-update. That's the other way round, of course, but it's picking up a signal from one of the internet time servers instead of the network.
The other long shot would be to get someone to call the device if you haven't received a call since the clocks changed. My home phone system gets its time from BT, but only updates when it's called.
Edited to add: I've just changed the time on my Tom Tom sat nav and if I tell it to synchronise (with the satellites), it goes back to BST, which is counterintuitive as I'd expect it to be on GMT if it was on anything permanently.