I keep getting calls from this number.  I haven't answered yet, but they never leave a message

heard some background noise like paperwork as someone about to speak and ask for money (as is similar to past phone calls where I actually answered).  I hung up after not having heard anything else after my "hello".

I don't know anything, but I blocked my phone from sales and unkown number

I called the # back to find that it is the Missing Children Society of Canada.  The toll free number to have your phone number removed is 1-800-704-1645 (option 9).