Principal role of the USSD service.
USSD (Unstructured Supplementary Service Data) is a technology used for transmitting of information over GSM networks. As a session based service it can support a sequence of information exchange. It works in two modes: push mode and pull mode.
USSD Phase 1 (pull operation), described in GSM 02.90, handles mobile initiated requests. In this phase no real time session is held, as it is only able to pass information from a mobile phone to the USSD service with a confirmation.
USSD Phase 2 (push and pull operation), described in GSM 03.90, handles network-initiated requests and establishes interactive dialogue between USSD application and mobile phone. If a user don’t perform any actions the connection is released by a time out. This phase also allows to push information from network to a users’ handset.
Often overlooked, USSD technology helps users quickly and easily access information and services, and provides endless business opportunities for mobile service providers.
How does it work? User’s perspective.
1. User enters a short USSD service number on the mobile phone (e.g *100#) and press “call”.
2. USSD service receives the request and responds by sending a menu to the user.
3. The user enters a character that corresponds with his/her selection.
Usability
• Fast response. Unlike other short-message protocols which use store-and-forward technique, it offers session-based communication. Information is sent directly from a mobile phone to an USSD platform during a real-time session, avoiding SMSC in the processing path. As a result, a user don’t experience any latency while sending requests to a service.
• Worldwide access. All USSD request are rooted back to the home network. Dialing an USSD number while in roaming in another network will lead to a service which is in home network. This helps users to access their favourite services from other countries.
• Simple to use. USSD service is simple to access through practically any GSM mobile phone. A user initiate session by dialing a short code on a default mobile screen which starts with * followed by digits and terminated with # (e.g. *111#). Some of these codes request a single piece of information while others deliver a series of text menus with further navigation.
Functionality
USSD is ideal for a menu-driven applications, therefore it has great potential for mobile banking to perform such operations as balance check, account transactions, payments etc. It is important to note that USSD is not a menu on a mobile phone, but just a bearer for text selections and menus. These menus and texts are not stored on a handset or a SIM card. That’s significantly improves level of security on the users’ side as opposed to SMS messages when data is saved on a device.
Here is the other cases of using USSD:
■ Balance enquiry as alternative to IVR
■ Callback Services
■ Money transaction
■ Informational services ( weather, news, stock market etc.)
■ Voting
■ Reservations
■ Service management (activation / deactivation)
■ Notifications
■ Mobile advertising
USSD + SMS + WAP
USSD can serve as a convergence point for SMS and WAP services. As simple and straightforward service, USSD requires almost no user experience – anyone who can type on mobile devices can use it. With the help of it, service providers can encourage users to visit WAP sites. For example, USSD can respond to a user’s request with an SMS, which can contain a WAP link. This link may lead to a WAP site that is somehow connected with the USSD service which is being used.
Key Benefits
For mobile users:
• Simple to learn, direct access from any default mobile screen.
• Fast response time.
• Supported by 99% of mobile devices on the market.
• Worldwide access to services.
For service providers and operators:
• Can be quickly implemented to existing infrastructure.
• USSD can easily engage users.
• Fast mobilization of business for service providers.
• Cheaper than sending SMS.
