Currently there is an email flying around that all cell phone numbers are being released to telemarketing companies this month so you should expect to start receiving sales calls on your dime.  The email goes on to say to prevent this you should call an 888 number from your cell phone (and only your cell phone) to block this action.  

This email has been going around the internet for years – it’s an Urban Legend!

With the heavy fines and consequences cell providers would endure*, I wouldn't count on your number being released to anyone - especially telemarketers.

Of course there are ways these groups can get your number, maybe you used it as a contact number for yourself while signing up for another product, etc or someone had it before you. It is possible for telemarketers to get your number, so I would add your name to the DO NOT CALL list via – but do it via http://www.donotcall.gov/default.aspx.

*THE FREEDOM OF INFORMATION ACT and the THE PRIVACY ACT OF 1974 - http://www.usdoj.gov/oip/foiastat.htm or http://www.usdoj.gov/oip/privstat.htm  or check out how the FCC controls what cell phone company's can do at:
http://wireless.fcc.gov/