The iSync application lets you automatically transfer information from iCal calendars and Address Book contacts on a Mac to your third-party mobile device. For example, your third-party mobile phone device can be synchronized using iSync to display your latest Events, and your contact list can always be up-to-date with your Mac.
Apple has discontinued iSync in Lion and it is no longer included as part of the OS or available as a separate download from Apple. If you upgraded to Lion from Snow Leopard, iSync is also removed from your Mac as part of the upgrade process.
By using iSync v3.1.2 from Snow Leopard it is possible to continue syncing iSync compatible phones in Mac OS X Lion 10.7.x.
If you are using iCloud, you will need to turn it off for your Contacts and Calendars to be available locally to iSync.