To make your phone sync well, we strongly recommend hosted Exchange Server with Direct Push technology if you are using a task list with full Exchange Server integration. To sync, refer to your task list manufacturer’s web site for Exchange syncing instructions. If this is not available, see if a service like Nuevasync will make the tasks show up on your Windows Mobile phone:

If you are really determined, you can also sync manually using ActiveSync on your desktop or laptop. However, manual syncing is unreliable—it will corrupt your data sooner or later. Back up often!