USSD Technology: What's it about?

A: She finally replied to my DM and my data finished in this middle of the night? What do I do now, Aliyu?
B: Don’t you have money in your account to buy airtime?
A: Yeah, but I can’t access my GTB Internet Banking or Mobile Banking App
B: You don’t need to – Just dial *737*AirtimeAmount# and thank me later.

Credit: Pexels

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USSD Definition

USSD commonly known as "Shortcode" stands for Unstructured Supplementary Service Data. It can be described as a GSM technology (protocol) that allows real-time or instant communication between a mobile phone and a program in the network operator’s computer. In simple terms, USSD is the number we dial usually starting with either asterisk (*) or hash (#) followed a by number(s) and end with a hash (#) on our mobile phones.

In truth, we cannot operate our mobile phones effectively and efficiently without the use of USSD. It makes the work of the mobile network provider and you the subscriber, a doddle.

The term USSD and shortcode will be used interchangeably in this write-up.

Different Types and Kinds of USSD

There are three different kinds of USSD. We have;

1. Reserved Bill: This type of USSD is free for use by the subscriber. An example is a shortcode we use to query our airtime balance or subscribe to a data bundle.
2. Standard Rate: This type of USSD requires a subscriber to pay a standard fee to complete a request. An example, the shortcode you sent to vote for your favorite participants during a programme like Big Brother Naija.
3. Premium Rate: This type of USSD requires a premium fee from the subscriber to complete the request. The shortcodes we send to win N100 million, Generator or house etc.

We have two kinds of USSD, PULL and PUSH.
Pull is when a subscriber dials a shortcode to request for a menu containing list operations or execute a task. Push is when the network provided displays a pushed message, usually adverts paid by businesses.

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Use of USSD

You’ve been using USSD on your phone to complete certain transactions such as checking balance, subscribing to a data bundle or using it as a banking platform.

1. Standard Supplementary Services: We use USSD to query our airtime balance, subscribe to data bundle and others alike.
2. Mobile Network provider Value-Added Services: MTN, AIRTEL or Glo PUSH adverts to our mobile devices using USSD Technology.
3. USSD Applications: We use USSD for Mobile Banking to query account balance, transfer funds, and banking related operations.
   Typical Example of USSD Usage
                                                      
   Screenshots of my mobile phone showing how I used USSD PULL to request a list of banking operations from my bank.

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How it works

You can’t use just any shortcode to access a service. To implement USSD service, you need to work with a mobile network service providers and the body that regulates the Telco industry in your country to assign a USSD to you after signing an agreement and obtaining a license in some cases.

Every Company/Business has a unique shortcode that users can use to access their service. We can refer to those shortcodes as domain names we use to access websites on the internet. USSD requires a gateway to transmit the USSD messages between the mobile subscriber and the mobile network provider while connecting through SMPP (Short Message Peer-to-Peer) protocol.

I will use GTBank mobile banking for a demonstration of how a typical USSD operation works.

When you dial *737# from your mobile phone, a request is sent to your mobile network (MTN, Airtel, 9mobile or Glo) and then directed to a USSD gateway (still owned by the network provider or third party) which understands and processes the USSD shortcodes. The USSD gateway will add the relevant parameters (programmed by the developer to uniquely identify the chosen service) to the Call Back URL and then direct the URL to the GTBank Application Server where the application/database of accounts is being hosted. The Call Back URL plus the attached parameters will help the application determine the actual menu to send to your mobile device through SMPP containing the list of all the operations you can perform or a response if you completed a transaction, that’s if the USSD session is still active.

A typical USSD Architecture
A simple USSD architecture showing the workflow of a USSD operation. A reference of the above GTbank scenario.


Free sketch of a simple USSD architecture drawn by me.

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Conclusion

According to the National Communications Commission (NCC), there are about 236 million connected Mobile (GSM) lines in Nigeria and only 144 million are active subscribers as at December, 2017.

Banks, Fintech, and other companies/business are leveraging USSD Technology to give Africans better services and experiences without internet or at no data cost.

References

1. USSD: Wikipedia
2. USSD Technology: Intarget
3. USSD Gateway: Mycloudcode