I called this # and they hung up without answering.
They may also be using the toll free # +1 800-228-3552.

This number shows up constantly and nobody leaves a message.  Does anyone know who this is?

I don't know who it is, but I do know they called and asked about whether or not I had called Canada Post in regards to a package I recently sent to my in-laws. Unfortunately, I was out at the time they called and the person who answered didn't know I had called in regards to a package, so they told the person "no".

I called this # and they hung up without answering.They may also be using the toll free # +1 800-228-3552.