You usually cannot directly call back a No Caller ID number
Check your phone’s recent call log for any hidden details
Contact your carrier and ask if they can trace the call
Use your carrier’s call return or anonymous call rejection services if available
Dial *69 in some regions to return the last incoming call
Use a call tracing service if your carrier offers one
Block unknown or private numbers if the calls are unwanted
If the calls are harassing or threatening, report them to law enforcement
Let calls go to voicemail and wait for the caller to leave a message