USSD

What is USSD?

USSD (Unstructured Supplementary Service Data) is a communication protocol used by mobile phones to communicate with a service provider’s GSM (Global System for Mobile Communications) network. It is used to send text between a mobile phone and an application program in the network. USSD can be used for WAP browsing, prepaid callback service, mobile-money services, location-based content services, menu-based information services, and as part of configuring the phone on the network.

USSD runs over the same GSM signalling layer that powers HLR lookups — the mechanism behind BSG's Number Verifier. For more on that layer, see Maintain a Clean, Relevant Database with HRL Service.

How does it work?

USSD works by sending a special code to the service provider through the GSM network. The service provider then responds by sending a text message back to the phone. The user can then enter information into the phone or select a menu option from the text message. The service provider then processes the information and responds with the requested service.

USSD messages can contain up to 182 alphanumeric characters and the time it takes from a request to a response is 2 seconds while it takes 6 seconds for an SMS to reach a mobile phone.

What is the difference between USSD and SMS?

The main difference between USSD and SMS is that USSD is an interactive protocol, while SMS is a non-interactive protocol. USSD allows two-way communication, while SMS is a one-way communication method. USSD messages are sent and received instantly, while SMS messages take longer to be sent and received. USSD messages are also shorter in length than SMS messages.