To fix address book sync issues in Outlook and other services or devices, follow these steps:

Troubleshooting Steps:

1. Update Outlook:
   • Make sure your Outlook application is up-to-date with the latest patches and updates.
   • Sometimes changing Outlook can fix sync issues.
2. See Internet links:
   • Make sure your device has a stable and working internet connection.
   • Synchronization requires an Internet connection to communicate with the server.
3. Verify account settings:
   • Double-check to make sure the account settings in Outlook are set correctly.
   • Confirm that the server settings for contact synchronization are correct.
4. Restart Outlook:
   • Close Outlook completely and reopen it to see if the problem persists.
   • Sometimes a simple reboot can fix synchronization issues.
5. Check out the folder:
   • Make sure you have the appropriate permissions to access and modify contact folders.
   • Allowing the wrong folder can prevent synchronization.
6. Clear the cache and reset settings:
   • Try clearing the cache and resetting the settings related to address book synchronization.
   • This allows you to troubleshoot configuration issues that can cause problems.
7. Discontinued add-ins: 
   • Third-party add-ins can sometimes interfere with Outlook’s syncing processes.
   • Let the add-in run briefly and check if the sync works properly.
8. Fix Outlook Data File:
   • Use the built-in Outlook repair tool (ScanPST) to repair any corrupted data files.
   • Corrupted data files can cause synchronization problems.

Address Book Sync in Outlook:

You can also try the following steps to specifically handle address book synchronization in Outlook: 

• Manual Synchronization: Start manual synchronization in the Outlook application to install updates.
• Check contact sources: Make sure the contacts you are trying to sync are stored in a valid address book source (e.g., Outlook.com, Exchange, Google Contacts).
• Reviewing Error Messages: If you receive an error message while trying to synchronize, review it for specific information that can guide troubleshooting steps.

Other tips:

• Contact Support: If the problem persists, consider getting official Microsoft support for Outlook.
• Back up contacts: Back up your contacts to avoid accidental data loss before attempting major changes.

If you follow these steps, you should be able to find and resolve most address book synchronization issues between Outlook and external services or devices. If the problem persists, consider getting more expert help from Outlook’s official resources or professional IT services.