USSD Short codes, also known as marketing campaign codes, are memorable digits that are 3 to 6 digits long. SMS test numbers (e.g. 2331) which are widely used in Premium Rate services such as reality show voting, donation services, outdoor advertisement, TV and Radio contribution and/or competitions. They are increasingly being used in marketing and corporate campaigns as they are much easier to remember than long telephone numbers (10 digits). They enable customer data to be captured and provide a measurable response rate.