Who called from 4042235799

Keeps calling my work phone and not leaving a message

Calls and know one on line.

Calls and when answered know one there.

This number keeps calling my office phone, not leaving messages and when I call back rings and rings then beeps like a fax.  Who is it?!?

same as other post.... sent to voice mail no message... called later went to voice mail no message again. called it back and got a fax beep.