How to sync iCalendar with Office 365 calendar

First of all, you need to setup your Outlook account on your iPhone. To do so, please go to this link and follow the steps in the very first section (the one titled: Setup Exchange email on an Apple iPhone, iPad, or iPod Touch).

Here is the link: http://office.microsoft.com/en-001/office365-suite-help/set-up-email-on-apple-iphone-ipad-and-ipod-touch-HA102818554.aspx

Note: In step #8 above, please ensure that "Calendar" switch is turned ON.

Now that your account is setup, please allow a few seconds for sync to occur. The next is to make the new calendar visible in iCalendar by following the steps below:

1. Start iCalendar
2. Open your calendars list by tapping on Settings > expand Calendars section > tap "My Calendars"
3. Find the new calendar and tap on it in order to make it visible in iCalendar (a check sign should appear next to it)
4. Tap "Done"
5. Tap "Done"

Your Outlook events should now appear in iCalendar.