calling USSD with text attached on android

How is it possible to call a USSD with a text attached on android. For example: *455*1*Hello*0#. I have looked around the web and couldn't find any solution for it. The only question that seems to resemble what I want to achieve was asked 9 years ago here. Surely there is some API or a workaround available in Android after all these years?

• I also tried to URI.encode all characters that aren't a number. No luck there as explained here.
• I have thought of interacting with the dialog to insert the text but that will take a significant amount of time for the user which renders the app useless.
• Neither ACTION_CALL intent nor placeCall API does anything to solve this.
• Is it not in the protocol to send a text on the initial request?
• TelephonyManager::sendUssdRequest(String, TelephonyManager.UssdResponseCallback, Handler) was introduced in API 26. I am targeting API 21 and above. I haven't checked if that solves it yet tho.

Take a look at this library seems to be what you are looking for.

Library is called VoIpUSSD by romellfudi incase link doesn't work.