What is USSD And What it Does

Full form of USSD is Unstructured Supplementary Services Data that allows for the transmission of information via a GSM network. Contrasting with SMS, it offers real time connection during a session. A USSD message can be upto 182 alphanumeric characters in length. Unstructured Supplementary Service Data allows interactive services between a MS and applications hosted by the Mobile Operator. These messages are composed of digits and the #, * keys, and allow users to easily and quickly get information/access services from the Operator.

Characteristics of USSD:

• A USSD message can be upto 182 alphanumeric characters in length
• Unlike SMS, USSD is a session oriented service
• Simple and easy to send. No need to go into any menus and options. Just directly entered on the default mobile screen.
• USSD works on all GSM handsets of Phase II or later.
• There will not be any latency in request and response as we experience in SMS based services
• The functionality will be the same even while roaming as the USSD messages always routed back to Home HLR.
• USSD is supported by WAP, SIM Application Toolkit and CAMEL enabling scope for many applications.
• Works in two modes: pull mode and push mode.

Applications:

• USSD can be used as a WAP bearer.
• Used for menu based content services like news, weather, sports etc
• Used for prepaid callback service enabling prepaid roaming a better service
• Used in location based content services
• Used in SIM Application tool kit based applications.

Source : telecomspace.com