This step may seem obvious but you would be surprised at the number of people who give out their cell phone number inadvertently. Do not share your cell phone number, for example, when you enter a contest or fill out a survey. Most contests are designed to compile names, addresses, emails, and telephone numbers so that they can be used by or sold to telemarketers.
Block your cell phone number from being transmitted
There are two ways to block your number from being transmitted. The first way to prevent your number from being sent is to preface the number that you are calling with "*67". This prefix allows for per-call blocking. So, to dial the number (123) 555-1212, you would dial: *671235551212. This feature is usually called "Per call blocking" or "Selective blocking".
The second way to block your number is to order per line blocking from your cell phone provider. Per line blocking will always prevent your number from being displayed on a caller ID device. IT WILL NOT BLOCK YOUR NUMBER IF YOU DIAL 911 or if you call an 800 NUMBER. If you want to show your number, dial "*82" and then the number you want to call.
Register your cell phone number in the DO NOT CALL REGISTRY
The National Do Not Call Registry gives you an opportunity to limit the telemarketing calls you receive. To add your number, call the following number from your cell phone: 888-382-1222. It will only take a minute of your time. You must call from the cell phone number you want to have blocked. You can not call from a different phone number.
Once you register your phone number, telemarketers covered by the National Do Not Call Registry have up to 31 days from the date you register to stop calling you. The Federal Trade Commission manages the National Do Not Call Registry. Telephone numbers placed on the National Do Not Call Registry will remain on it permanently due to the Do-Not-Call Improvement Act of 2007, which became law in February 2008. More than 157 million phone numbers are on the National Do Not Call Registry. The Do Not Call Registry is not just for cell phones. You can register ANY telephone number on which you do not want to receive marketing calls.