What you are calling is a computer or what they call Interactive Voice Response (IVR) listening. Each key pressed has its own assigned tone. The computer matches the tone with the number pressed. The computer then routes that customer support call to a human that is pre-assigned to that number that has the skills to answer the questions of the number chosen by you. The technical term is called Dual-Tone Multi-Frequency signaling (or DTMF). In customer support centers humans are assigned to those (queues) numbers based off of skills sets that have knowledge in different areas of the business.