It rings out. They don't leave a voicemail. They ring the next name on the list.
By the time you've climbed down and called back, the job has already been quoted by whoever picked up. It wasn't lost on price. It was lost on a ringtone.
This is the part nobody sells you. A web firm builds the site. An SEO firm gets you found. Both of them consider their job finished the moment the phone rings — which is the exact moment yours starts going wrong.
Answering is not a technology problem. It's a staffing problem you can't afford to solve with staff. So it gets solved with an answering machine, which is to say it doesn't get solved.