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 SIMPLE CRM calendar you want to add in the "Server" field. The full address is into SIMPLE CRM -> MAIN TOP MENU -> ADMIN -> USERS -> ICAL
Tap the "Next" button.
Enter a custom description for the SIMPLE CRM calendar and tap "Next" once more to finish adding it to your iPhone.