Short Code
The first methods I’m going to talk about is short code. Have you ever seen a TV commercial or printed ads like “text XXXX to 00000 to get today’s most popular joke”? Or maybe, do you remember the “American Idol” show where you can vote for your faborite contestants by dialing a short code? These are the perfect examples of short code. Short codes, also known as short numbers, are special numbers that usually 5-6 digits which can be used to address SMS and MMS message from mobile phones(Wikipedia).
Although short code has been widely used in European countries for long time, it was until 2002 when “American Idol” show adapted this method that got really popular in the states. Since then, short codes which often associated with automated services(Wikipedia) are now widely used for opt-in mobile campaigns in the U.S