Call Tracing

I have landline phone service with Xfinity.

Yesterday I received a crank call from an anonymous phone number, so I did a "call trace" to it, *57.

Right afterwards I received a message that said the call trace was was successful.

So I would like to know if I can get the phone number that called me.

If the call trace was successful, then you should have the phone number somewhere in your data base

I called customer service, but the people I spoke with didn't know how to get me the phone number

So can you please get the phone number for me?  And please speak to someone who knows how to do it.