Calling back an anonymous number?
If this is a recurring problem you can forward your calls to a toll-free number which will reveal blocked IDs. When I needed to bust a private caller I forward unanswered calls to a toll-free number instead of voicemail deposit. Then don’t answer private calls. Caller ID cannot be blocked to toll-free numbers. You can use the toll-free provider’s voicemail or forward the call to another line from there. The toll-free provider I use is Kall8 which immediately sends an email with the caller’s name (if available) and number. You can have this sent to your phone. This provider charges $2 a month and 6.9 cents a minute.
