It's tempting to judge a campaign by cost-per-call alone, but that single number hides almost everything you need to know before committing more budget.
Average handle time tells you whether calls are substantive conversations or quick disqualifications — a cheap call that ends in eight seconds isn't actually cheap.
Conversion rate by source shows you which traffic is worth scaling and which is quietly dragging your blended numbers down without anyone noticing.
Repeat caller rate and duplicate flags catch traffic quality issues before they become fraud disputes — small spikes here are an early warning, not noise.
And time-to-connect matters more than most advertisers assume: campaigns with slower routing consistently show lower conversion, even when every other input looks identical.
Look at these five together before scaling spend, and you'll catch problems weeks before they show up in a monthly report.