Start with the leak, not the ad spend
Most home-services businesses buy more ads before they answer the phone reliably. That is backwards. Here is the math on a single missed call.
The model
Take a business doing $4M/yr with an average job value of $650 and a 30% close rate on booked estimates. If they miss 12 calls a week after hours — a conservative number — that is roughly $192K/yr in modeled lost revenue walking straight to a competitor who picked up.
Why this beats more marketing
Every one of those callers already had intent. You paid to generate that demand once. Answering the phone is the cheapest customer acquisition you will ever run — and it is a fixed cost, not a per-lead one.
Fix the answer-rate first. Then buy ads.