They called me 6 time in 3 minutes on cell my number. Didn't know number so I did not answer and they left No messages.  I finally had time enough to block number.
Call 1.  12:23 pm  central time
2.  12:24 pm
Calls. # 3-4-5.  12:25 pm. I hit decline on these 3 times,  they immediately called back split second.
6.  12:26  pm  able to block number this time