If you own a mobile phone, then you may have knowingly or unknowingly interacted with USSD. USSD simply stands for Unstructured Supplementary Service Data.
It is a simple technology that allows people to send and receive text messages over a GSM mobile network.
It is quite similar to SMS but unlike SMS, it provides a real-time channel for two way transmission of text data from one end to the other. Sending and receiving messages feels more like a chatting interaction.
How USSD Works Typically, a USSD operation works in two ways. It can either be mobile initiated (USSD Pull) or network initiated (USSD Push).
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A Mobile Initiated USSD request requires a mobile user to enter a valid USSD Service Code (eg *100#) and send the request to a Mobile Network Operator.
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A Mobile Network may also initiate a USSD requesting a mobile user to provide particular information or provide a notification message (without a response expected).
The diagram below dipicts the message flow between a mobile user and a USSD Application in a mobile initiated USSD operation.
To deploy a USSD application, you require either a direct relationship with a Mobile Network Operator or through an intermediary gateway often reffered to as an Aggregator.
A USSD application can be developed in any programming language of choice. The example below is a simple example developed based on the SMSGH USSD API. You can find details on how to use the API from the documentation page.
Why You Should Consider USSD
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USSD is seen as one of the most viable alternative delivery channels for delivering Valued Added Services especially in the Financial Services sector. USSD is the the backbone of one of the most successful innovations to come out of Africa - Mobile Money Services. It has expanded the reach of banking and other financial services to many folks who where previously left unbanked.
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It is a very simple technology that is accessible via any GSM mobile device.
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It is also less expensive compared to other delivery channels like the internet.
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It is fast and instant.
This is just a brief introduction of USSD to beginners however if you want to know more about the USSD specification, you can checkout the 3GPP website.