Size the daily volume of incoming voice calls: a PM estimation exercise

Estimate how many calls are received in a single day. Define what you are counting, build the number from stated assumptions, and sanity-check where you land. ```hint Pin down "received" Settle early whether a call that rings but goes unanswered counts, and whether calls made through messaging apps count alongside carrier calls. Then build from the people who receive calls, not from network equipment you cannot see. ``` ### Clarifying Questions - Should the estimate cover the whole world, or a single country such as the United States? - Do app-based voice calls (for example over WhatsApp, FaceTime or Google Meet) count, or only calls on mobile and landline networks? - Is a call received once it rings the recipient's phone, or only once someone answers it? - Should calls into businesses and call centers be included, or only calls that individual people receive? ### What a Strong Answer Covers - A precise definition of a received call and of the population being sized, stated before any arithmetic - An equation that segments receivers by how much they use the phone instead of applying one flat average - Labeled, round-number assumptions and arithmetic the interviewer can follow step by step - A sanity check that converts the total back into calls or minutes per person per day - The assumption that drives most of the uncertainty, and how far the answer moves if it changes ### Follow-up Questions - How does your number change if only answered calls count, or if spam and robocalls are excluded? - How would you estimate the peak number of calls in progress at the same moment, for example to size network or call-screening capacity? - If this estimate were feeding a decision about an automatic call-screening feature on Android phones, which part of it would you refine first, and how?