You can call back a private number in five ways. They are as follows: Calling back a private landline number by dialing *69 and #69 for private mobile phone numbers, a private number can be called back within 30 minutes of receiving the call. Analyzing and verifying the call logs provided by the service provider where the private number might be mentioned. Search the number through reverse number lookup. Third-party applications can be utilized to get private numbers and call back. Call tracing services can be availed to unmask private numbers and can call back.