Most trades businesses have no idea how many calls they miss. Not a rough figure — no idea at all.
The calls that go to voicemail do not show up anywhere you would look, and the ones that ring out leave no trace whatsoever.
Think about a normal Tuesday. You are under a sink at ten past two. Phone is in the van. It rings, and you carry on, because stopping means losing the fitting you are holding.
By the time you check it, there is a missed call from a number you do not recognise and no voicemail. That is the whole event.