Unstructured Supplementary Service Data

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Unstructured Supplementary Service Data is a capability of all GSM phones. It is generally associated with real-time or instant messaging type phone services. There is no store-and-forward capability that is typical of 'normal' short messages (in other words, an SMSC is not present in the processing path). Response times for interactive USSD based services are generally quicker than those used for SMS.

As a comparison, USSD is similar to telnet, while SMS is similar to mail.

USSD is typically used as a 'trigger' to invoke independent calling services which don't require the overhead and additional usage costs of an SMSC, such as a callback service (e.g. cheaper phone charges while roaming), or interactive menuing service (e.g. stock quotes, sporting results).

USSD is a standard for transmitting information over GSM signalling channels. It is mostly used as a method to query the available balance and other similar information in pre-paid GSM services.

Example USSD codes:

• *101#
• *109*72348937857623#

After entering an USSD code on your GSM handset, the reply from the GSM operator is displayed within a few seconds.

USSD is the base of some payment methods such as Mobipay.

[edit] Companies Working On USSD

• Opencode Systems Ltd
• Comverse
• Pyro Networks Pvt Ltd
• Bharti Telesoft Ltd
• Cellicium
• Sicap
• Truteq Wireless
• Flash Media Group

[edit] References

Unstructured Supplementary Services Data. Unstructured Supplementary Services Data. Retrieved on 2005-08-27.