what is a ussd code code example

Example: ussd

// Vist https://www.aat.co.za/always-active-mobile/ussd/
AAT specializes with ussd and I have worked with them in the past
Offer really great support and their API is easy to use.
Works very well in prod.
https://github.com/azandazama/MenuPlus is a PHP library I coded up 
to help get started with creating ussd apps with the AAT Mobile API

// Visit http://tms.flashmedia.co.za/tms3-web/user/ussd.jsf?routeId=19182 
This site gives you a free ussd string and allows you to code 
up your own ussd solution in PHP/Python, great docs also. 
Not recommended if your looking for something to go with to prod.