Outlook Contact Sync
While you can fully manage your contacts in Outlook, you can also save your contacts to the default Contacts app on iOS and Android. This allows you to easily see the name of a contact when you receive a call or text message from them and view all of their contact information directly in the built in Contacts app.
On both iOS and Android, open the Outlook app and go to Settings. Select your Office 365 account and then turn on Sync Contacts.
Changes to these contacts should be done within the Outlook app only. Changes made to them in the built in Contacts app may not work or synchronize back to Outlook.