They are used for bulk communication in marketing, passing targeted information to customers, alerts and notifications, responses to queries from companies, interactive media communication, automated voting, ringtones, betting among others.

USSD Codes

A USSD is an interactive * session-based protocol. USSD messages travel over GSM signaling channels and are used to query information and trigger services. Unlike similar services (SMS and MMS), which are store and forward based, USSD establishes a real time session between mobile handset and application handling the service. USSD uses * to indicate a continued request and # to forward.

Types of Applications:

  • Menu based requests: The user can send a Process Supplementary Service request (PSSR) to the home zone which will forward this, under guidance from the Gateway, to the correct application. Then, the application sends an acknowledgement back to the user.
  • Voice Chat: Using the same process as above, one can use voice chat. This is highly useful when VoIP enabled phones are not available.
  • Advertising: The application can advertise their product using USSD which is less invasive than telemarketing.
  • Roaming: This has huge advantages while roaming. This is because USSD services are well available in roaming networks and all the USSD messages are directed towards the subscriber's Home Network itself, thus, same set of services that are available in home network can be given in visited network too, giving subscribers a Virtual Home Environment (VHE).

USSD is commonly used to query information and trigger services. These include:

  • prepaid callback service
  • mobile-money services
  • location-based content services
  • menu-based information services