Check your phone’s recent call log for the hidden number, if your carrier reveals it
Use your carrier’s call trace or anonymous call tracing service
Contact your mobile or landline provider and ask about blocked or private numbers
Enable spam and caller ID protection features in your phone settings
Use a third-party caller ID app that can identify some unknown callers
Call back only if the number becomes visible in voicemail or call history
Ask the caller to identify themselves by text or voicemail
Report harassing or threatening calls to your carrier and local authorities
Dial *69 or your local last-call return code if supported by your carrier
Request a call trace code from your provider if the calls are repeated or abusive