Free/Busy Coexistence User Guide
Enable calendar availability lookups between Google Workspace and Microsoft 365 for seamless meeting scheduling.
Introduction
Free/Busy coexistence enables users on different calendar platforms to see each other's availability when scheduling meetings. This is essential during migrations or for organizations that need long-term interoperability between Google Workspace and Microsoft 365.
With Cloudiway's Free/Busy solution, users can check the availability of colleagues on any platform without needing to know which system they use. The coexistence server handles all cross-platform queries automatically and transparently.
Key Benefits
- No Installation Required: Cloud-based solution with no software to deploy
- Transparent to Users: Availability lookups work like normal - users don't need training
- Multi-Platform Support: Works with Google Workspace, Microsoft 365, and Exchange On-Premises
- Quick Setup: Typically configured in one day for 2 tenants
- Long-Term or Migration: Ideal for both permanent coexistence and migration projects
Enterprise Coexistence Solution
Free/Busy works alongside GALSync for complete cross-platform coexistence including address book synchronization.
View Enterprise CoexistenceHow Free/Busy Works
The Cloudiway coexistence server acts as a bridge between calendar platforms, enabling availability queries across different systems.
Communication Flow
User Request
↓
Source Platform (Google Calendar / Outlook)
↓
Cloudiway Server (Routes the query)
↓
Target Platform (Microsoft 365 / Google Workspace)
↓
Availability Data Returned
End User Experience
When a user creates a meeting and adds attendees from another platform:
- Google Calendar: Click "Find a Time" tab to see attendee availability
- Microsoft Outlook: Click "Scheduling Assistant" to see attendee availability
Users don't need to know which platform attendees are using - the system handles it automatically.
Supported Platforms
Free/Busy coexistence works with any number and combination of the following platforms:
Architecture Options
| Architecture | Description |
|---|---|
| Full Cloud | Google Workspace ↔ Microsoft 365 (both SaaS) |
| On-Premises/Cloud | Exchange On-Premises ↔ Google Workspace or Microsoft 365 |
| Hybrid | Microsoft 365 as intermediary to Exchange On-Premises |
| Shared Domain | Same email domain on two platforms (requires special configuration) |
- Google-to-Google queries (same platform)
- Free Gmail accounts linked to professional addresses
- Exchange 2010 and earlier (contact Cloudiway for alternatives)
Prerequisites
Before configuring Free/Busy coexistence, ensure you have the following:
Cloudiway Account
An active Cloudiway account with Free/Busy subscription.
Google Admin Access
Super Admin access to Google Admin Console for Calendar Interop configuration.
Microsoft 365 Admin Access
Global Admin or Exchange Admin for PowerShell configuration.
Licensed Service Accounts
Google: Licensed account with Calendar App enabled. Microsoft 365: Exchange license (not Kiosk plan).
Service Account Requirements
| Platform | Requirements |
|---|---|
| Google Workspace | Valid Google license with Calendar App activated. Service account with domain-wide delegation. |
| Microsoft 365 | Exchange Online license (not Kiosk/F1). No special permissions required beyond the license. |
Step 1: Create Connectors
The first step is to create Free/Busy connectors in the Cloudiway platform for each tenant you want to connect.
Navigate to Connectors
Log in to the Cloudiway platform and go to Connectors.
Add Google Workspace Connector
Click Add Connector, select Google Workspace, and enable FreeBusy in the Coexistence Products section.
Configure Google Service Account
Choose between Cloudiway Google Service Account (recommended) or Custom Google Service Account (Expert Mode). Enter your domain names and administrator account.
Add Microsoft 365 Connector
Click Add Connector, select Microsoft 365, and enable FreeBusy in the Coexistence Products section.
Configure Microsoft 365 Connector
Enter your Tenant information (Tenant Name, Domain Names), Entra ID Application credentials (Application ID, Client Secret Value), and Administrator Account details (Email Address, Password).
Step 2: Configure Cloudiway
After creating connectors, activate them and configure the Free/Busy settings.
Activate Connectors
- Navigate to Free/Busy > Configuration
- Select each connector and click Activate
| Option | Description |
|---|---|
| Active | Toggle to enable or disable the connector for Free/Busy queries. |
| Details / No Details | When set to Details, the response includes calendar event details (subject, location). When set to No Details, only Free/Busy status is returned without event information. |
Global Settings
Navigate to Free/Busy > Global Settings to configure general Free/Busy options:
Configuration Options
| Option | Description |
|---|---|
| Query All Users | When enabled, any user's availability can be queried. When disabled, only users in the approved list can be queried. |
| Manage Users Automatically | When enabled, Cloudiway automatically syncs the user list from tenant groups. When disabled, manage users manually via portal, CSV, or API. |
| Lookup Details | Controls whether to return only availability status or include additional calendar details. |
Generate Credentials
Navigate to Free/Busy > Credentials to view and manage your authentication credentials. These credentials are used by Google and Microsoft 365 to authenticate to the Cloudiway platform.
| Field | Description |
|---|---|
| Consumer key | The username/account used to authenticate. Used as the "Exchange Role Account" in Google Calendar Interop settings. |
| Consumer secret | The password for authentication. Used as the "Password" in Google Calendar Interop settings. Click the key icon to generate a new secret. |
| Free busy alias | Your unique Cloudiway service URL (e.g., customeralias.cloudiway.com). This URL is used in the Exchange Web Services URL field in Google and in the PowerShell commands for Microsoft 365. |
Step 3: Configure Google Workspace
Configure Google Workspace to query availability of Microsoft 365/Exchange users through the Cloudiway server.
Access Calendar Interop Settings
Open Google Admin Console
Go to admin.google.com and sign in with your Super Admin account.
Navigate to Calendar Settings
Go to Apps → Google Workspace → Calendar.
Open Calendar Interop Management
Click on Calendar Interop Management.
Configure Exchange Web Services Settings
Enable Calendar Interop
Check the box to Enable Calendar Interop features
Enter the following values provided by Cloudiway:
| Field | Value |
|---|---|
| Exchange Web Services URL | Provided by Cloudiway Services |
| Exchange Role Account | Your Cloudiway Consumer Key |
| Password | Your Cloudiway Consumer Secret |
Click Save
Step 4: Configure Microsoft 365
Configure Microsoft 365 to query availability of Google Workspace users through the Cloudiway server using PowerShell.
Prerequisites
- Install the Exchange Online PowerShell module
- Have Global Admin or Exchange Admin credentials ready
Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName [email protected]Configure Availability Settings
First, run the availability configuration command (required once):
New-AvailabilityConfig -OrgWideAccount [email protected]
Replace [email protected] with any existing Exchange Online user.
Add Availability Address Space
Set up the Cloudiway credentials and add an availability address space for each external domain you want to query:
# Set up Cloudiway credentials
$adminCredsId = "Consumer key"
$adminCredsPassword = "Consumer secret"
$securePassword = ConvertTo-SecureString $adminCredsPassword -AsPlainText -Force
$adminCreds = New-Object System.Management.Automation.PSCredential($adminCredsId, $securePassword)
# Add the availability address space
Add-AvailabilityAddressSpace -AccessMethod OrgWideFB `
-ForestName externaldomain.com `
-Credentials $adminCreds `
-TargetAutodiscoverEpr "https://[cloudiway-server-url]/autodiscover.xml"Replace:
Consumer key- Your Cloudiway Consumer Key from the Credentials pageConsumer secret- Your Cloudiway Consumer Secret from the Credentials pageexternaldomain.com- The domain of the Google Workspace tenant[cloudiway-server-url]- The Cloudiway server URL provided by Cloudiway Services
Verify Configuration
Check that the availability address space was created:
Get-AvailabilityAddressSpace | Select ForestName, TargetAutodiscoverEpr | flRefresh Address Book (Optional)
Force a refresh of the address book to ensure contacts are visible:
Set-AddressList -Identity "All Users" -ForceUpgradeStep 5: Test Free/Busy
After configuration, verify that Free/Busy lookups work correctly between platforms.
Test from Google Calendar
Create a New Event
In Google Calendar, click to create a new meeting.
Add External Attendee
Add an attendee from Microsoft 365 (their email address).
Click "Find a Time"
Click the "Find a time" tab to view availability.
Look for "Refresh All"
If Calendar Interop is working, you'll see a "Refresh all" button. Click it to fetch availability.
Test from Microsoft Outlook
Create a New Meeting
In Outlook, create a new meeting request.
Add External Attendee
Add an attendee from Google Workspace. The contact must exist in the GAB (via GALSync).
Open Scheduling Assistant
Click "Scheduling Assistant" to view availability.
Verify Availability Shows
The external user's busy/free times should display in the calendar grid.
Cloudiway Test Tool
Cloudiway provides a built-in test tool to verify connectivity:
- Navigate to Free/Busy > Test
- Enter a user email to query
- Click Test
- Review the detailed output showing each step of the query process
Key Features
Cloudiway Free/Busy includes several features to manage and customize the coexistence solution.
User List Management
Navigate to Free/Busy > Resource List to manage users and resources:
- Automatic: Cloudiway syncs users from tenant groups automatically
- Manual: Upload CSV files or use REST API for precise control
- Query All: Allow any user to be queried without maintaining a list
Scheduling and Logs
- Pull Scheduler: Refresh user list membership automatically
- Execution Logs: Track all operations for troubleshooting
- Credential Management: Secure password generator for credentials
Rooms and Resources
Free/Busy coexistence supports querying availability of meeting rooms and resources across platforms, with some limitations.
Microsoft 365 Rooms
Microsoft 365 rooms and resources can be booked from Google Calendar:
- Users can query availability of M365 rooms from Google
- Users can book M365 rooms directly from Google Calendar
- Room bookings are processed normally through Exchange
Google Rooms
Workaround for Google Rooms
If you need external users to book rooms:
- Migrate the Google rooms and resources to Microsoft 365
- Microsoft 365 does not have the same booking limitation
- External users can then book M365 resources from any platform
Troubleshooting
Common issues and solutions when configuring Free/Busy coexistence:
Authentication failed error
Verify that credentials are correct:
- Check the Consumer Key and Consumer Secret in Google Calendar Interop settings
- Ensure the service account has necessary permissions
- Verify the Exchange Web Services URL is correct
User not found error
The target user must be properly configured:
- Ensure the user exists in the user list (if "Query All Users" is disabled)
- For Microsoft 365 queries, ensure the contact exists in the Global Address Book (use GALSync)
- Verify the email address is spelled correctly
AvailabilityAddressSpace not configured error
This error occurs in Microsoft 365 when the availability address space is missing:
- Run
Get-AvailabilityAddressSpaceto check existing configurations - Add the missing domain using
Add-AvailabilityAddressSpace - Ensure the ForestName matches the external domain exactly
Connection timeout
Network connectivity issues:
- Verify outbound HTTPS (443) is allowed to Cloudiway servers
- Check firewall rules aren't blocking the connection
- Test connectivity using the Cloudiway built-in test tool
Changes not taking effect in Google
Google Admin Console changes may take up to 24 hours to propagate:
- Wait 24 hours before concluding there's a problem
- Try testing with different users
- Clear browser cache and try again
"Refresh all" button not appearing in Google Calendar
The Calendar Interop feature may not be enabled or propagated:
- Verify Calendar Interop is enabled in Google Admin Console
- Check that the settings have had time to propagate (up to 24 hours)
- Try using a different browser or incognito mode
Our team can assist with configuration and provide the server URLs and credentials for your environment.