Isn't CEST 2 hours before UTC? If you'll notice, the timezones printed are not the same.
Java does tend to want to work with UTC, since that provides a common base, no matter where in the world you are.
In an actual device, the time would normally be set by an incoming signal from the carrier. I don't know specifically about systems in your area, or for that matter, even the one I use, but on land-line phones with called name/number delivery (Caller ID), there's a timestamp in the ASCII ID code that comes after the first ring of an incoming call. For mobiles, for all I know, they may pick up the time as part of the process where they seek out and identify their location to the carried. Then again, some phones have GPS, which means that they could get the atomic-precision time from the GPS satellite system.
So, in summary, the time in a cellphone "should" be quite accurate, but I don't guarantee it.The main thing is to make sure you're aware of timezone conversion requirements.
And your English is just fine. The only thing you need to remember is that the
word "I" is always capitalized, even though "you" and "we" are not. We're not big on logical!