[sohab]

[Curlyben]

YOU can't but if they are a nuisance then inform your provider as they have tools that could help.

[cajalat]

I'm also not aware of a way to trace the call without involving your phone provider or the authorities.

But what you can do is block calls from unidentified, unlisted, anonymous, private, etc numbers. Most phone companies offer that feature through the use of codes that you dial to enable/disable features. If an anonymous caller tries to call you then they will get a recording telling them to unblock their number first before the call goes through. You can try *77 to enable Anonymous Call Rejection and *87 to disable that feature. If those codes don't work (most companies use the same codes) then you can check with your phone company for specifics.