Scammers hack into your friends’ accounts and post a link on your Facebook profile, with titles such as: “Can you beat my IQ of 138? Click here” or “What is the next number in this series - can you solve it?”– and a link is provided.
Opening the link brings you to a game challenge site, where you have to put in your phone number, to start the game. This is similar to many other cases such as the Free laptop ads, IP winner ads, or text quizzes (with answers to extremely easy questions, such as “Who is the president of United States”?).
By typing in your phone number, you are automatically registered to Premium texting. That means you will receive daily text messages that will cost you $2/piece. By the time you realize that, you will have been charged a lot of money.
How to avoid: contact your friend who accidentally spammed you and ask him if he really did play that game/ quiz. Also, contact your mobile provider to opt out the scamming registration (or depending where you live, you can text back the word “Stop” and you automatically opt out). But above all, never enter your phone number anywhere on the Internet unless you are absolutely sure the site is safe.