If the number appeared in your "Recents" list but you don't know who it belongs to, use the following methods:
No iOS feature or app can magically reveal a truly hidden (No Caller ID) number. However, for unidentified numbers that are simply not in your contacts, a combination of: how to see unknown number on iphone
Navigate to your Billing or Usage section to view detailed call logs. These logs frequently display the actual phone number, even if it appeared as "Unknown" on your device screen. 3. Use Third-Party Caller ID Apps If the number appeared in your "Recents" list