How do I fix Unknown Caller Bug in macOS Tahoe Phone App?

Three approaches in order of safety: (1) Force a Contacts Sync (Free); (2) Reset the "identityservicesd" Process (Free); (3) The Pro "Identity" Cleanup. Full Terminal commands and System Settings paths are inside each section.

Is this fix confirmed for macOS Tahoe 26.2?

Yes — verified on macOS Tahoe 26.2. Article is updated when Apple ships a point release that changes the symptom or fix.

How to Fix Unknown Caller Bug in macOS Tahoe Phone App

Symptom: When receiving a call on your Mac (via iPhone continuity), the caller ID shows as "Unknown Caller," even if they are in your Contacts. Or, the Phone app randomly quits during a call.

TL;DR fix

Start with Fix 1: Force a Contacts Sync (Free). If the issue persists after that, try Fix 2: Reset the "identityservicesd" Process (Free). Full Terminal commands and step-by-step instructions are in each section below.

Why this happens

This is a synchronization bug between the macOS Tahoe "identity daemon" and iCloud Contacts. The system fails to pull the VCF data fast enough to display the name during an incoming call, defaulting to "Unknown."

Recommended Troubleshooting Tool

Before proceeding with manual fixes, we recommend using CleanMyMac X. Quickly identify high CPU apps and optimize system memory with one click.

Fix 1: Force a Contacts Sync (Free)

Force the identity daemon to "re-read" your iCloud address book.

Sign Out of iCloud

Go to System Settings > [Your Name] > Sign Out.
*Note: Choose "Keep a copy" of your data to be safe.*

Sign Back In

Restart your Mac.
Sign back into your Apple ID.

Toggle Contacts

Ensure "Contacts" is toggled ON in the iCloud settings list.

Fix 2: Reset the "identityservicesd" Process (Free)

This process handles the "Who is this?" logic for FaceTime and Phone calls.

Open Terminal

Go to Applications > Utilities > Terminal.

Kill the Daemon

Type: killall identityservicesd
The system will automatically restart the process.

Wait for Re-index

Give the system 5 minutes to re-map your contacts to their phone numbers.

Fix 3: The Pro "Identity" Cleanup

When corrupted contact "ghosts" are blocking the sync.

If you have duplicate contacts or old, broken VCF files, the Tahoe identity daemon will "timeout" while searching, resulting in "Unknown Caller."

Recommended Tool: CleanMyMac X

- Contacts Cleanup: CleanMyMac X has a module to find and merge duplicate contacts and repair the local database files that the Phone app relies on.

- Privacy Module: Clear out the "Call History" and "Chat Caches" to ensure the system is starting with a clean slate.

Tested and documented by the MacDebug team — about MacDebug. See also Photoshop & Adobe Apps Crashing on macOS Tahoe, Fix macOS "No AirPlay Found", or browse all guides on macdebug.