USSD Protocol for GSM phones and Its Uses

Unstructured Supplementary Service Data (USSD) is a service used by GSM cellular telephones for 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.

Upto 182 alphanumeric characters in length, USSD messages, unlike SMS messages, create a real-time connection during a USSD session. The connection remains open, allowing a two-way exchange of a sequence of data.

An USSD message has no store and forward capability like that of SMSs. It is supported by almost all GSM phones. A typical USSD message starts with an * (asterisk) symbol followed by digits and ending with a # (pound) symbol. The message may also contain additional * symbols in it. These digits are usually commands to perform certain tasks.


Examples where we make use of USSD codes are while viewing balances on our mobile phones or recharging our account. USSD codes are also used to avail services like PNR Enquiry from Mobile Phones, Mobile Banking, Using Facebook From Mobiles Without an Internet Connection etc.


Some Popular USSD Codes are as follows:

*139*# - display's Indian railway PNR inquiry results, short-code working across all the Indian operators network.

*325# - Facebook on USSD, working most of the countries, across all the GSM operators.

*595# - State Bank of India USSD banking service.

*141# - display's user's balance on the Vodafone network