# Introduction

USSD, which stands for Unstructured Supplementary Services Data, is a protocol that allows for the transmission of information via a GSM network. 

Users enter a USSD string and press call to send the message. A typical USSD message starts with a \* followed by digits which indicate an action to be performed or are parameters. Each group of numbers is separated by a \*, and the message is terminated with a #. 

For example, in Kenya, to find out what your airtime balance is on Safaricom, a user will dial \*144#. Unlike SMS, USSD messages create a real-time connection during a session, that remains open, allowing a two-way exchange of a sequence of data.

This documentation explains details about a service that allows for users to send in reports to ushahidi deployments via USSD on Ushahidi v3.

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Ushahidi Platform USSD Service Demo
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*Source codes for the Ushahidi Platform API USSD Service is available* [*here on GitHub.*](https://github.com/ushahidi/platform-api-ussd-service)

#### *You can read about*  [**My Google Summer of Code Experience (GSoC) with Ushahidi**](https://medium.com/studevs/my-google-summer-of-code-experience-gsoc-with-ushahidi-d314b634c6e1)