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.

{% embed url="https://drive.google.com/open?id=1-3LGJRNMH1Qi9ZAdconb3raRmPR4UzNE" caption="Ushahidi Platform USSD Service Demo" %}

Source codes for the Ushahidi Platform API USSD Service is available here on GitHub.__