It sound to me like the last person who had your number signed up for a lot of contests and free stuff, and had to give his phone number to get them.  Those pests are now calling you.

Assign this number a "no ring" ring tone.  It won't stop the calls, but it will let you sleep through them.

Just got a new cell number and within the first few days started getting telemarketing calls. In the middle of the night got 5 calls from this number. What is with these companies - haven't they heard of new marketing?