tyntec

tynpedia

U:

UDH
UMTS
Unicode
Universal services
USSD
 

USSD
USSD (Unstructured Supplementary Service Data) is generally associated with real-time or instant messaging-type phone services and is available in all GSM phones. There is no store-and-forward capability, such as is typical of other short-message protocols (in other words, an SMS-C is not present in the processing path). Response times for interactive USSD-based services are generally quicker than those used for SMS. USSD is typically used as a 'trigger' to invoke independent calling services that don't require the overhead and additional usage costs of an SMS-C, such as a callback service (e.g. cheaper phone charges while roaming), or interactive data service (e.g. stock quotes, sports results).

USSD is a standard for transmitting information over GSM signaling channels. It is mostly used as a method to query the available balance and other similar information in pre-paid GSM services. The function that is triggered when sending USSD is network-dependent and depends on the specific services the operator is offering.