Changing your number, however, probably won't stop the spam calls. I just went through this a couple months ago. The first time I changed my Verizon number I was assigned one that, come to find out, was listed on a bunch of escort service websites. Got lots of interesting texts and voicemails with that one. Changed it again and didn't have any spam calls for a couple weeks, but they soon started up again and I get almost 1 per day on average. I didn't change my original number because of spam calls, but I got them with the old one and still get them with the new one. My one piece of advice if you do change your number - Google it before giving it out to anyone to make sure it isn't associated with any "adult" sites. If it is you can just change it again right away before going through the hassle of notifying everyone about your new number and having to explain why you changed it multiple times.
And as others have pointed out, it's very easy to change yourself on their website.