Only works on calls from land lines. VoIP not handled.

TrapCall is designed to unmask phone numbers that have intentionally been blocked or masked using *67. TrapCall works by utilizing the conditional call forwarding feature offered by your carrier.

However, the call you received was an "Unknown" call. These numbers cannot be unmasked because they typically do not contain a valid Caller ID. Unknown numbers typically indicate that the telephone company may be having a problem with the Caller ID number in some fashion. This happens most commonly with VoIP calls and calls that may originate from outside of North America. We alter the Caller ID to display 229-518-6462, which you can add to your blacklist.

Not so hilarious about TrapCall: Reveal No Caller ID, v6.0.160