BlackBerry Curve 8520 Smartphone allows users to change the display of time format from 12 hour format to 24 hour or vice versa. This can be changed using settings available as part of BlackBerry 8520 options screen.
Press the menu button on BlackBerry 8520
Select Options from the list of displayed menus.
In the Options screen, navigate to Date/Time.
In the Date/Time screen, navigate to Date/Time section.
And you set your preferred display format by selecting 24 hour or 12 hour for the Time Format drop down field.
If you are presented with Changes made screen, then select Save to apply and confirm the Time Format changes.