This document discusses how call tracking can help businesses maximize their return on investment from advertising by providing insights into which ads and marketing channels are driving the most calls and customers. It explains that call tracking works by assigning unique phone numbers to each advertising source, then routing all calls to the business while recording data on call volume and sources. This allows businesses to see detailed reports and analytics on the performance of each ad, location, number, and day of the week to understand which efforts are most effective and where marketing dollars should be spent.