Mac users can publish calendars that can be shared online with friends and family using the iCal application. Shared iCal calendars, denoted by a ".ics" extension in the file name, must be accessed over an Internet connection. If you have an iPhone, you can subscribe to an ICS calendar feed directly from your phone without having to go through the iCal application or iTunes to configure sync settings.
Tap on the "Settings" icon from the iPhone's home screen.
Tap on "Mail, Contacts, Calendars" from the list of device settings.
Tap the "Add Account" button and select "Other" in the list of account types.
Choose the "Add Subscribed Calendar" option at the bottom of the screen.
Enter the full address or file path of the ICS calendar you want to add in the "Server" field. Make sure to include the ".ics" extension at the end of the address or path. Tap the "Next" button.
Enter a custom description for the ICS calendar and tap "Next" once more to finish adding it to your iPhone.