Possibly only for T-Mobile and AT&T!
Ever wanted to unmask an unknown number calling your cell phone?
Well, go ahead and sign up for TrapCall (FREE)!
I just signed up. What they do is change your call forwarding option from your voice mailbox to their phone number (I am guessing voice mailbox will still work of course). Once you decline an anonymous call, it'll go to their #, then your phone will ring again with the REAL number this time! How cool is thatttttt!!?!?!?!?
One thing that you do need is call forwarding from your provider...
tl;dr- unmask private callers to your cell by signing up for free here:
Signup Link:
https://www.trapcall.com/signup
Main Website:
http://www.trapcall.com/
how they make money?: there are different plans besides the free one. some you can get the name of the anonymous number, and some you can even get billing name&address. they also have dif calling goodies like spoofcard and liarcard...