You can use shared Office 365 Calendars in OnceHub via your OnceHub account. Shared calendars can be used when you connect via either a personal connection or a corporate Office 365 connection. 

Sharing calendars allows OnceHub to create bookings in and retrieve busy time from calendars that are not owned by you.

In this article, you'll learn about using shared calendars in Office 365 Calendar. 

Shared calendar options

Each connected calendar in OnceHub can be used either as a main booking calendar, a calendar to retrieve busy time from, or an additional booking calendar. This can be configured for each Booking page under the Associated calendars section.

With shared calendars, the same three options apply. The only added requirement is that the calendar owner grants you the necessary permission level within Office 365 (Figure 1).

Figure 1: Sharing and permissions

• To use the calendar as a Main booking calendar, you must be granted Editor or Delegate permission level in Exchange/Outlook.
• To use the calendar for Busy time retrieval, you can be granted any permission level in Exchange/Outlook. 
• To use the calendar as an Additional booking calendar, you must be granted Editor or Delegate permission level in Exchange/Outlook.

Which calendars can be shared?

Most Outlook calendars can be shared. Your ability to share calendars depends on the sharing policy specified by your Office 365 administrator. 

You can share calendars on the same domain, or share calendars across different domains. To use shared calendars on the same domain, follow the sharing instructions below.

To use calendars shared across different domains, the person given access to the shared calendar must accept the sharing by clicking the link or button in the email notification. These calendars will be automatically added to the calendar list in the Calendar section of each Booking page. You do not need to do anything else to use these calendars in OnceHub. Sharing calendars across domains requires specific settings in your Office 365 configuration.

Using shared calendars when connected with a personal connection

Follow these steps to use a same-domain shared calendar when connected with a personal Office 365 Calendar connection.

1. Ensure that the calendar owner shared their main calendar with you as Editor or Delegate. Additionally, sub calendars may also be shared. Each calendar must be shared individually.
2. Add the calendar owner's email address in the Associated calendars section of each Booking page. All calendars and sub-calendars shared with you, will appear in the calendar list.
3. Select how each calendar will be used: Main booking calendar, Busy time retrieval, or Additional booking calendar. If your permissions are insufficient, ask the calendar owner to change your permission level.

Using shared calendars when connected with a corporate connection

Follow these steps to use a same-domain shared calendar when connected with an Office 365 corporate connection.

1. Ensure that the calendar owner shared their main calendar with your dedicated mailbox as Editor or Delegate. Additionally, sub-calendars may also be shared. Each calendar must be shared individually. Note that all corporate account members will gain access to all shared calendars.
2. Add the calendar owner's email address in the Associated calendars section of each Booking page (Figure 1). All calendars and sub calendars shared will appear in the calendar list.
3. Select how each calendar will be used: Main booking calendar, Busy time retrieval, or Additional booking calendar. If your permissions are insufficient, ask the calendar owner to change the permission level.
   Figure 2: Associated calendars section of the Booking page