It is not that hard for Recruited to locate you and get your phone number. I get calls all the time at work from Recruiter either trying to recruiter me or get the name of someone else at my work who maybe a better fit for their jobs. Basically all they need is your name and where you work, and as people pointed out Linked in provide both piece of information to them. I bet if you look at who is looking at your profile you will see it was a recruiter.
Everyone once in a while I get a call on my cell by a recruiter which means someone I know gave them my number.