SMS.ac is generally considered a fraud website based in San Diego, California. They employ a special sort of social engineering in their attempt to capture new members; by spamming all the Hotmail-contacts of a new members (usually without his/her knowledge). The current Chairman and CEO is Michael C. Pousti.
When the person has become a member, SMS.ac automatically adds them to several mobile chatgroups; and charges the member's mobile phone account a small fee for each Short message service text (known as a SMS) sent to the registered phone. Former employees of SMS.ac have reported that these SMS-messages are generated from SMS.ac centrally; making it appear as if real people are actually chatting through the SMS.ac-service.
Attempting to cancel ones membership at SMS.ac is also very hard - if not impossible.