Two numbers you know, and two you estimate. No email, no signup. The answer appears as you move the sliders.
It's multiplication, not a study. Missed calls, times the share who don't call back, times your hit rate, times what a job is worth, times fifty-two weeks. You can check every step above, and if a number looks wrong to you, move it. The point is your figure, not ours.
We deliberately didn't pick the scary defaults. There's a widely-quoted claim that 85% of people never call back after an unanswered call, and we've left that slider at 50 instead. We went looking for the study behind the 85 and could not find one. Every citation we followed led to another blog rather than to research, so we set the default where you can defend it.
Someone answering every call would fix it, and that is what the front desk does: your line answers, asks what they need, offers your open slots, and books the one they press. Callers who hang up at the greeting still get the text-back, written the moment the call rings out and sent from your own number on your tap. Most people will answer a text when they wouldn't call back.
That's the front desk — you can watch it run on sample data before deciding anything. It comes with your website plan; its answering line is billed separately by Twilio.