This isn't spam. If it keeps calling you then someone you know is using it as a prank call. It's a website to help find a lost phone. It will call any number if the user hits enter.
This is http://www.wheresmycellphone.com/ you enter your phone number when you lose your cell and it makes the phone ring. If you did not sign up then maybe someone else mis typed their own number. OR someone is pranking you.
I think people getting calls from this number may want to know. That someone might be playing a joke on them. After doing some research I found that this number is a number that comes from a web-site called " Where`s My Phone " You type in anyones phone number and it calls.