Daylight Saving Settings
 

When we have daylight saving, our computer and mobiles (and probably some other devices) "knows" that its daylight saving and it either ask us if we want to change the time... or it just does it automatically...

Where does the signal to change daylight saving time come from?

Is it pre-programmed into the phone/computer when we select our timezone, or is it linked to the phone company / windows / mac server?

It changes automatically and without notice. It is completely determined on your timezone because there are some states/countries that don't use DST of course.

In the case of mobile phones, when they connect to a local tower they retrieve the day/time information. As far as Windows is concerned, it doesn't require a check with a server. It's already coded into the software. That's why when the US recently changed their DST dates, Windows required a patch.

Ohh OK...

the thing that sparked my question was I read an article where Telstra (one of our major telecommunication company) got bombarded with complaints that it changed everyone's DST a week early...

And Telstra blamed it on the pre-settings of the software on the phone / blackberries...

So... I was just wondering how the settings come about...