How to stop these numbers from calling me?

These random numbers, probably telemarketers, keep calling me and i blocked all the numbers but notifications still pop up when they call. Today i had my battery charged all the way and after a few hours i came back and my phone was completely dead and when i turned it on i found out i had 40 missed calls from a random number. What should i do because it takes up a lot of my battery and also the notifications interrupt my music. Btw i have T-mobile android.