The calling phone number may not match with a contact name and the name is not shown in the following situations when an incoming call or SMS arrives:
- The phone number is defined twice in the People hub, the same number is found for two or more contacts (usually the last 6 numbers of the phone number are significant).
- The phone number is in different format than the number received in the incoming call. The phone number may have been stored in local format while the incoming call number is in international format (including country prefix), or vice versa. The number may not be properly matched with a contact name in this situation, depending on the device variant and the length of the calling number. In order to verify the correct format of the contact phone number (local or international), check the number which is shown when the call is received and edit the contact details accordingly.
If the problem persists, make sure your Nokia Lumia is running the latest software. For downloads and assistance, go to your local Nokia website.