Stupid telemarketers?

So i got a call on my cell phone at like 9 in the morning, i didn't recognize the number (702-765-0315) so i let it ring. They didn't leave any voicemail. I then google searched the number and found out that it is a telemarketer. I just got called again by them like an hour ago. This time i answered and immediately hung up. If they call again, i am going to ask politely to be removed from their caller list. I just went to register my cell phone on the do not call list. Is there anything else i should do?