USSD

USSD (Unstructured Supplementary Service Data) is a standard service in GSM networks, allowing to organize interactive interaction between a network subscriber and a service application in the mode of sending short messages.

The USSD service is supported in GSM Phase 1 and Phase 2 ( session initiation by the USSD application). The USSD service is in many respects similar to SMS , both services use the format of short messages for data transmission. However, USSD is mainly intended for the exchange of messages between the subscriber and additional services, in the simplest case, the autoinformer service of the settlement account, while SMS is mainly used for the exchange of short messages between subscribers.

USSD, unlike SMS , does not have an intermediate database and does not guarantee re-delivery of messages, which makes instant messaging. USSD is a session-oriented technology, the entire dialogue between the subscriber and the application is conducted within one session. The analogue of the USSD service is the IVR- based system ( Interactive Voice Response ), in contrast to which the USSD does not have voice connections, only the signaling channel is used. Data exchange in the USSD session is more visual and operational.

The main direction of using the USSD service is to provide subscribers with the opportunity to receive additional information from applications and manage these applications. USSD works on all existing GSM phones, with the exception of the earliest models of 1998-1999.

Each operator uses its own USSD commands, for example, in order to find out the balance of a mobile phone account. ^[one]