In places where the digital divide runs deep, accessing essential services can be a challenging task. For example, checking the status of a government subsidy application or registering for health services in remote areas can be nearly impossible without internet access or a smartphone. Unstructured Supplementary Service Data (USSD) offers a solution by allowing individuals to access critical information through a simple code dialled on their feature phones, bypassing the need for advanced technology. 

With minimal entry barriers, USSD offers a practical and inclusive solution for all – from rural health workers in Africa checking patient records to small business owners in South Asia applying for grants – bridging gaps and making vital services truly accessible. 

Understanding USSD 

USSD is a communication protocol widely used for real-time communication with mobile networks, distinct from Short Message Service (SMS) due to its operational nature. While SMS is asynchronous, USSD operates over the Global System for Mobile Communications (GSM) radio network, facilitating interactive sessions without the need for an internet connection. It enables users to interact with services through simple text-based menus, accessed by dialing a service code on their mobile phones. The protocol is session-based, meaning it provides a real-time, interactive dialogue between the user and the service provider. 

The primary advantage of USSD lies in its ability to function without requiring an IP layer or data connectivity; as long as a phone can make calls, USSD services can be accessed. This makes it particularly advantageous in regions with limited data infrastructure. 

USSD technology serves as a critical bridge between digital services and the practical realities of daily life. It enables ID-based service delivery, facilitating access to essential services such as life event registrations, healthcare protections, and financial resource management. With USSD, governments and organisations can ensure that essential services are available to residents who might otherwise be left behind in the digital divide. 

USSD offers several distinct advantages that make it a valuable tool for service delivery: 

01 No Custom Software Required: USSD does not require any custom software to be installed on the handset. The technology operates directly through the mobile network's standard services, ensuring that users can access services with minimal technical requirements. 

02 Works with Any Handset: USSD is compatible with any mobile phone that supports GSM connectivity, including both basic feature phones and advanced smartphones. 

03 No Internet/Data Service Required: Unlike internet-based services, USSD does not require an active data connection. 

04 Cost to Service Provider: Typically, the cost of using USSD is borne by the service provider rather than the end user. This cost structure can enhance service inclusivity, as users are not required to pay additional charges on their phone bills. 

Implementation Challenges 

Despite its effectiveness, deploying USSD for service delivery presents certain challenges: 

Design Considerations: USSD's text-based format must be designed to work across a range of devices, from basic feature phones with limited display areas to more advanced smartphones. 

Backend System Integration: Integrating USSD with backend systems poses a challenge due to the short-lived nature of USSD sessions, which typically last only one to two minutes. The backend system must be stateless to handle these brief interactions efficiently and accurately. 

MOSIP’s Approach: USSD Integration with Fayda 

MOSIP collaborated with the National ID Program, Ethiopia (NIDP) platform called Fayda. The USSD was set up using the local telecom provider to create a proof of concept for Fayda-based USSD- service delivery to the resident. This initiative showcases how USSD can be utilised to provide critical Fayda services efficiently, even in regions with limited technological resources.

MOSIP proposes making the following services accessible via USSD technology: 

01 MOSIP Registration Status Check: Users can dial a service code to check the status of their ID registration. The system maps the phone number to

the registration ID, eliminating the need for users to input lengthy identification numbers on feature phones. 

02 Virtual ID Generation: Users can generate an alias or virtual ID for one-time use, enhancing privacy and security. The virtual ID is sent to the user via SMS, following OTP-based authentication. 

03 Retrieving Lost UINs: In cases where users have misplaced their UINs, they can request retrieval through USSD. The system sends the UIN via SMS, mapped to the user's phone number for convenience. 

04 Language Selection: To cater to diverse linguistic needs, the system supports multiple languages, allowing users to select their preferred language for interactions. 

05 Life Events: USSD service in partnership with MOSIP identity API can be used for significant life events and support. After authentication, residents could register for maternity care, childbirth, or marriage. These registrations can be followed by manual healthcare visits or other essential services. By leveraging MOSIP's authentication, the identity of individuals requesting assistance can be reliably verified. 

Technical Architecture and Integration 

The technical integration of USSD involves several layers that are common infrastructure in a telecommunication network. The deviation begins at the respective SIP method and the SDP (Session Description Protocol). Most of the SDP systems allow us to define our content and interaction as XML’s. 

MOSIP’s solution architecture integrates with telecom service providers via various protocols, including SOAP XML and SMPP. This integration requires a robust backend system capable of managing USSD sessions and interfacing with the telecom infrastructure. 

The architecture includes a USSD gateway that communicates with the telecom’s Service Delivery Platform (SDP). This gateway interfaces with MOSIP’s backend through an intermediary layer that handles protocol adaptations and session management. MOSIP USSD Gateway bridges between Telecom's Service Delivery Platform (SDP) and MOSIP instance APIs. It translates Upstream USSD request into downstream API request, downstream API response into upstream USSD Response. Implements USSD Dialogs, manages persistent state for the dialogs per session basis. The design ensures compatibility with various telecom operators and their respective systems.
 

The deployment of USSD for resident service delivery embodies a significant step towards inclusivity and accessibility. While the technical and logistical challenges are substantial, the benefits of providing essential services to populations with limited digital access are profound. By leveraging the GSM network and simplifying user interactions, USSD has the potential to bridge the digital divide and ensure that crucial services reach the last mile.