Now that you are using the Outlook mobile app, you will want to merge your Exchange contacts with your iPhone. This will allow caller ID to work when you receive a call or a text message.
- Open the Outlook mobile app.
- Click on Inbox at the top of the screen.
- Click the gear in the lower left hand corner to open Settings.
- Click on Office 365 (your email address).
- Scroll down to Save Contacts and toggle the switch on.
- When you are prompted to save your outlook contacts, click on Save to my iPhone.
- Click OK to give Outlook permission to access your contacts.