Short answer
Call tracking shows which marketing produced each phone call by swapping the number shown to visitors from different sources. Done properly it does not affect rankings, because your real number stays on your Google Business Profile and remains visible to anyone looking.
Call tracking is the least glamorous thing I set up and the one I would keep if I had to drop everything else. For a plumbing business where most enquiries arrive by phone, it is the difference between knowing and guessing.
What it actually does
Most plumbing enquiries are phone calls. Websites can measure clicks and form fills easily, but a phone call leaves no trail, so the most important number in the business is the one nobody is counting.
Call tracking fixes that by showing different phone numbers to different visitors. Somebody arriving from your Google Business Profile sees one number, somebody from an ad sees another. All of them ring your actual phone, and you cannot tell the difference as the person answering. But the system records which source produced which call.
That is the whole idea. Everything else is detail.
What it lets you answer
The question that most plumbers cannot currently answer: which of my marketing actually produced work?
Once it is running you can see that thirty calls came from the map, six from the ads and four from the website. Suddenly the decision about next month’s budget is arithmetic rather than opinion.
It also shows you things you did not ask about. Which hours bring the calls. How many go unanswered, which is often an uncomfortable number. Which suburbs ring most.
The ranking worry
This is the objection I hear most, and it is a fair one, because consistent business details genuinely matter for local rankings.
The answer is that your real number stays on your Google Business Profile and stays visible to anyone reading your site. The tracking number is swapped in only for the specific sources being measured, which leaves your public details consistent everywhere they are checked.
Done carelessly, by replacing your main number everywhere including the profile, it can genuinely cause problems. Which is an argument for setting it up carefully, not for skipping it.
When it goes in matters more than people think
Week one, before anything else is changed.
If tracking goes in at the start, month three has something honest to compare against. If it goes in at month three, nobody can tell you whether anything improved, and you are left with a story about how things feel better.
That asymmetry is exactly why some agencies are slow about it. Vague beats specific when the work has not gone well. It is also why tracking goes in first here rather than being sold as an upgrade.
What it costs and what it saves
Call tracking is one of the cheaper things in a marketing budget, usually a small monthly fee.
Set against that, it routinely finds a plumber spending money on something producing nothing, or discovers that a channel everybody assumed was dead is quietly bringing the best jobs. One of those findings pays for years of it.
The number nobody wants to look at
Missed calls.
Call tracking records them, and the figure is often worse than expected. Calls at lunchtime, calls while you are under a sink, calls at ten past five.
That is uncomfortable, and it is also the most valuable thing the system tells you, because missed calls are jobs you already paid to generate and then lost for free. No amount of extra marketing fixes that. Answering the phone does.