Issue

During the migration from Google Workspace to Microsoft 365, users are split between two calendar systems, making it impossible to view each other's availability across platforms. This lack of calendar visibility leads to scheduling difficulties and increases the risk of double bookings during the coexistence period.

Assumptions

Calendar Availability Challenges During Migration

Key Limitations:

• Migrated Users: Once a user’s mailbox is migrated to M365, they use Outlook for email and calendar. They can see the calendars of other migrated users, regardless of region.
• Non-Migrated Users: Users still on Google Calendar cannot see the free/busy status of migrated colleagues in Outlook, and vice versa.
• No Native Sync: After migration, there is no native synchronization or coexistence between Exchange and Google Calendar.
• Manual Workarounds: Scheduling meetings across platforms requires manual calendar checking and coordination, increasing the risk of conflicts and inefficiency.

Typical Coexistence Duration:
This dual-platform situation can last up to three weeks, depending on migration waves.

Options Considered

Option 1: Workarounds Without Synchronization

• For Migrated Users:
  • Use Outlook to check availability of other migrated users.
  • To schedule with non-migrated users, open Google Calendar separately and check availability manually.
  • Send meeting invites from Outlook, but verify times in Google Calendar.
• For Non-Migrated Users:
  • Use Google Calendar and communication tools (e.g., Google Chat) to coordinate with other non-migrated users.
  • Cannot see Outlook calendars unless explicitly shared.

• Leverage via Change Management and user support

Option 2: 3rd Party Synchronization Tool

Potential Benefits:

• Unified Calendar View: Synchronizes events between Google and Outlook, reducing the need for manual checks.
• Improved Scheduling: Enables free/busy lookup across platforms, minimizing double bookings and missed meetings.
• Enhanced User Experience: Reduces confusion and administrative burden during the coexistence period.

Considerations and Limitations:

• Security & Compliance: Ensure any 3rd party tool complies with company policies and data privacy regulations (SIP Validation required)
• Temporary Need: The synchronization is only required during the migration window (3 weeks).
• Estimated setup time: up to 6-8 weeks
• Technical Complexity: Integration and support may require IT resources.
• Cost: Evaluate licensing and support costs versus the productivity gains (only 1 RFP ~100k euro)

See also

The following section describes relevant documentation: