Hello @
shamim,USSD was earlier implemented as one of the supported channels in RapidPro core, due to the long-term maintenance burden of the USSD code base compared to the currently actualized demand/implementation by programmers, support for USSD was dropped from the RapidPro core starting with v5 and above.
The good news is, there is a project started to implement support for USSD using an external channel built outside RapidPro which leverages RapidPro's generic External API channel for RapidPro versions >=v5
Please visit
Link Here to clone and follow instructions closes in the README to get started.
Note that the project is also currently in testing phase and bugs reports are welcome.
We shall be around to guide you through the set up in case you get stack.
Thank you