Your question is Phone Keypad Key Identification. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Describe a system to identify which key is pressed in a phone keypad.
Assume the input may come from microphone audio, keypad vibration, or other device sensors, and the output must be a key label with low latency. Focus on how you would frame the problem, choose the model pipeline, and handle noisy real-world inputs.