Who called from 6474959524

This person calls sometimes 4 times per day. He/she leaves no message except to beep my answering machine line for a prolong period of time.
Who is it that is making this call?

Another one of those spam call from +16474959524 on 16 June 2015 (11:58am) in Vancouver, Canada. Learnt to ignore any calls from out of Vancouver, BC.

who is this woman who knew my confidential telephone number and my first name?

Just received a call from this woman, second time in the last week. "Could i speak with John?" When answered, "this is John," she hangs up. Both times there is loud music in background.

keeps calling, i answered and no one on the line. Text for whom ever to stop and he/she called back again