I extracted the firmwire and analyzed how built-in apps are working and how they are using screen, keypad, network and other phone functions.
Then I wrote a small C app, that will show "PDP" in calculator, if I press any key. once that worked, I changed in calculator code and added more and more functionality of a basic app. Then added deepseep api call that will answer the question, but I was not able to capture api response.
The tricky part were handling API call responses, it was not fitting in small memory and the answer was stored somewhere in buffer which is difficult to findout. Once I figured that out, then added a small custom AI agent, that will connect deepseep API to native phone tools.