[saintcrook]

How to trace a private number when it leaves no trace on call-log (call register) of the mobile phone? Even no detail is found for that private number by the police when they acquired the Call Detail from the mobile company.

[J_9]

If the police cannot obtain the information, neither can you.

[saintcrook]

Whether an unlisted number and private number a same thing or different?

[Fr_Chuck]

Both, unlisted is a phone that a number is actually listed some place, many phones are no longer listed. In them, the phone is set to privacy, not to give out the number

[Alty]

Whether an unlisted number and private number a same thing or different?

Doesn't matter, neither one shows up on call display.

[Fr_Chuck]

And very odd if the police can not even find evidence of the call.