Most local businesses have one number everywhere, so every call looks the same. The ads, the Maps Pack, the yard sign and the referral all land in one bucket, and nothing can be judged.
Give each channel its own number and the picture changes in a month. You find the channel quietly producing nothing, and the one you nearly cancelled that is carrying the business.
The number that matters is not calls. It is booked jobs and what each one cost. That takes the call data and your own job outcomes in the same report.