Applies to Version 3, release build 20251212.1 of the IBSS Microsoft 365 Sync Service
For Sync Service to work appropriately, we do not recommend having either AddOrganizerToSubject or DeleteSubject set to TRUE in your organisation's Microsoft 365 Calendar settings. Learn more here: Set-CalendarProcessing (ExchangePowerShell) | Microsoft Learn
The IBSS Platform provides the IBSS Microsoft 365 Sync Service that ensures both systems—Microsoft and IBSS apps—are kept up to date, no matter where the change is made. Users can create and update meeting room bookings, and these will stay in sync across IBSS and M365 apps.
How it works
- IBSS uses the Microsoft Graph API to send space bookings to Outlook (M365) and keep them updated.
- (new in release 20251212.1) IBSS also appends specific IBSS metadata to the Outlook event. This enables consistent and prompt two-way synchronisation between IBSS and Outlook.
- It listens for any changes in Outlook using notifications (webhooks) and updates IBSS accordingly.
- A background sync service watches meeting room calendars in Outlook and creates or updates matching bookings in IBSS.
- IBSS manages recurring bookings by creating each instance as an individual event in M365. This offers flexibility but means some limitations applied to series-level changes. Each event must be updated individually.
- Meeting rooms have to be set up as Microsoft 365 resources for the Sync Service to work.
This keeps calendars in IBSS and Outlook always in sync.
Handling attendees
When any event is forwarded to either an M365 or IBSS space, attendees are handled as follows:
- If the person is a user within IBSS, they remain being an attendee.
-
Organisations can choose how they'd like external attendees to be handled (CreateVisitor variable):
-
CreateVisitor variable set to TRUE: If the person's account doesn't exist in IBSS, they are turned into an in-person visitor record and receive a visitor invitation (if enabled).
Useful when physical building access and visitor pre-registration are required. -
CreateVisitor variable set to FALSE: External invitees are added as an internal attendee, do not receive a visitor invite for the building, only the meeting invitation.
Best for organisations where external attendees are expected to join online only.
-
CreateVisitor variable set to TRUE: If the person's account doesn't exist in IBSS, they are turned into an in-person visitor record and receive a visitor invitation (if enabled).
When an externally hosted booking is forwarded to an M365 space:
- Owner & Host of the booking in the IBSS system becomes the first person to forward the meeting if they are an internal user to IBSS. If not, the booking is not created in IBSS.
- If the meeting is forwarded again by another internal user, the Owner & Host does not change.
✅ Supported scenarios
Scenario |
Action |
|---|---|
| Individual booking | |
| Book a single meeting room in IBSS | Appears in Outlook via Graph API. |
| Book a single meeting room in Outlook | IBSS is notified and mirrors the event. |
| Create a booking for an event where a bookable space is added later | Any space added to an event (post create) will result in IBSS creating a booking. |
| Reschedule a single meeting (from either system) |
The new time is synced to the other platform. |
| Add or remove attendees for one event (from either system) |
Attendees are updated on both platforms. A visitor record is created in IBSS if the attendee is external (not found as a user in the system). |
| Change subject or location of a single event (from either system) |
Synced across IBSS and Outlook.
If changing the location to another building, that building has to be configured in IBSS for the Sync Service to work. |
| Forward any event to an M365/IBSS space |
It will have a corresponding booking made for it.
⚠️ Note how the existing attendees are handled when the event is forwarded to IBSS:
⚠️ Note how booking owner and host change when the M365 booking is forwarded to IBSS:
|
| Check in into the booking during the early check-in period |
|
| Recurring booking | |
| Create a series of recurring bookings in IBSS | Each instance is created as a separate event in Outlook. Cancelling a series from Outlook will not be possible. |
| Create a series of recurring bookings in Outlook | IBSS creates corresponding series of bookings. Cancelling such series from Outlook is then enabled. |
| Cancel one meeting in a recurring series (from either system) |
The specific event is removed in both IBSS and Outlook. |
| Cancel the full recurring series from Outlook | All relevant events are cancelled appropriately in IBSS if the series was initially created in Outlook. |
| Booking on behalf of someone else | |
| Create or update a booking or a series of bookings as a delegate for another user | Synced across IBSS and Outlook. To update a booking on behalf of another user in Outlook, you need to have access to their calendar. |
❌ NOT supported scenarios for IBSS Microsoft 365 Sync Service v3
| Scenario | Action |
|---|---|
| Creating a booking in Unity or Inspire | Not synced back neither to Outlook nor IBSS as neither application uses a user’s Active Directory account to create a booking. |
| Checking out of a booking on Unity | While you can check in on Unity to a booking that is associated to an M365 booking, it is not possible to check out of it on Unity. The system cannot shorten the meeting in the user's calendar. |
| Create a recurring series of meetings in IBSS, and then cancel it in Outlook | Not supported as IBSS creates individual appointments in Outlook. |
| Cancel the full recurring series from IBSS | IBSS doesn't offer an option to cancel the whole series. Users can manage it from Outlook only and with the condition that the booking series has been initially created in Outlook. |
| Update all future events in a series in IBSS and/or change the recurrence pattern (for example, from weekly to fortnightly) | IBSS doesn't offer an option to update the series. Users can manage it from Outlook only. |
| Create a booking in the past from Outlook | IBSS cannot create bookings with a start time in the past and will reject the creation of such booking. |
| Attach files or MS Teams meeting links | Not supported in IBSS bookings. |
| Create a linked spaces booking | Not supported neither as a single booking nor as a series of bookings. |