This is strange behavior. You can perform 2 tests to find where the problem is coming from.
First, test the mobile interface from your desktop. To do this, enter www.your_url.com/epesi/mobile.php This will give you the mobile interface on your desktop. Log in and test it and see if the times are correct. Then on your mobile phone, select the desktop interface. Again log in and test to see if the times are correct. My guess is the time will be the same on your phone weather you use the mobile interface or the desktop interface.
I just tested adding an event with my mobile phone, the time was OK. It sounds to me like you have a problem with time settings on your server.