A phone system can reject a call before anyone hears it ring, and the only symptom is that the phone seems quiet. Spam filters, forwarding rules, a number flagged in error, a carrier setting nobody remembers changing. This is how to find out whether calls are getting through. Ten minutes and two phones.
Every call rang, was answered, and is in the log. The line works. Put the test on the calendar monthly. Settings drift.
A call rang and was answered but is not in the log. The tracking is not seeing calls it should. That means your reports undercount the phone, and any decision made from those reports is made on a smaller number than the truth.
A call went straight to voicemail during business hours. Every lead that called at that moment left a message or hung up. Most hang up. Find out why the forwarding did not reach a person.
A call did not connect, or was rejected. There is a block somewhere between the caller and you: a spam filter set too aggressively, a number flagged by a carrier, a routing rule pointing at a dead line. This is the silent one. It has been costing calls every day since it started, and nothing in any dashboard would have shown it.
The numbers on the website, the listing and your signage are different. Not necessarily a problem, if they all ring through and are all tracked. A problem if one of them goes somewhere nobody is watching.
Every dashboard you look at counts calls that got through. None of them count the ones that did not. Call your own number from a stranger's phone once a month, and you will know.