This number keeps calling.

Called my business line. I did not answer. No voice mail left. I called back (from a different phone - a "throwaway cell phone"). After long pause it finally rang. An obviously non-phone company message came on sounding the three tones and a voice stated that I had reached a non-working number. 60% to 75% of the incoming calls to my business line are either scams or telemarketers. This number is obviously one or the other.