Page 48 - ITU-T Focus Group Digital Financial Services – Consumer Experience and Protection

ITU-T Focus Group Digital Financial Services
Consumer Experience and Protection

USSD messages are up to 182 alphanumeric characters in length. USSD messages create a real-time connection
during a USSD session. The connection remains open, allowing a two-way exchange of a sequence of data.
This makes USSD more responsive than services that use SMS.
Messages sent over USSD are not standardized:

Normally, USSD is used in the format *nnn# as part of configuring the phone on the network. In order to
transfer text messages via USSD to another mobile network, a special USSD gateway is required which mobile
operators not normally provide.

USSD is sometimes used in conjunction with SMS. The user sends a request to the network via USSD, and the
network replies within the same USSD session with an acknowledgement of receipt.

Subsequently, one or more mobile terminated SMS messages communicate the status and/or results of the
initial request. In such cases, SMS is used to "push" a reply or updates to the handset when the network is
ready to send them. In contrast, USSD is used for command-and-control only.

All mobile phones of phase II or later have USSD capability.

USSD is generally associated with real-time or instant messaging services. There is no store-and-forward
capability, as is typical of other short-message protocols like SMS.
USSD is specified in GSM 02.90 and in GSM 03.90.

USSD Modes:

• Mobile-initiated: USSD/ PULL or USSD/ P2P
when the user dials a code from mobile terminal

• Network-initiated: USSD/ PUSH or USSD/A2P
when the user receives a push message from the network

USSD can be used e.g. for prepaid callback service, mobile-money services, location-based content services,
menu-based information services, and as part of configuring the phone on the network.

B.2 Use Case #2

In addition to use case #1, the following underlying techniques can be taken into account. Even basic smart
phones will provide services based on these techniques.

B.2.1 WAP

Wireless Application Protocol (WAP) is a technical standard for accessing information over a mobile wireless
network. A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.
WAPs that use displays and access the Internet run what are called microbrowsers -browsers with small file sizes
that can accommodate the low memory constraints of handheld devices and the low-bandwidthconstraints
of a wireless-handheld network.
Although WAP supports HTML and XML, the WML language (an XML application) is specifically devised for small
screens and one-hand navigation without a keyboard. WML is scalable from two-line text displays up through
graphic screens found on items such as smart phones and communicators. WAP also supports WMLScript. It
is similar to JavaScript, but makes minimal demands on memory and CPU power because it does not contain
many of the unnecessary functions found in other scripting languages.

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