CPD (call progress detection)

Call Progress Detection (CPD) is the dialer's ability to interpret what is happening on a line right after it dials. Did the call ring out? Did it hit a busy signal, a fast-busy congestion tone, a network error recording, or did someone actually answer? CPD listens to those tones and signals and labels the outcome, and that label is the foundation everything else in the dialer is built on, from how a lead gets dispositioned to whether an agent is connected at all.

It is easy to confuse CPD with AMD (answering machine detection), so here is the clean split: CPD decides whether and how the call was answered, and AMD goes one step further to guess whether that answer was a human or a recording. CPD leans partly on Answer supervision from the carrier — a network signal that the far end truly connected and is not just ringing — and partly on listening for audible tones such as CONGESTION when that signal is missing, delayed, or unreliable, which it often is on cheaper routes.

Why it matters for pacing

Good CPD keeps your dialer honest and your reports trustworthy. It separates a true Live answer from a ring that simply timed out at the Dial timeout mark, and it stops calls from sitting open and burning a channel when they really hit a dead network. In VICIdial the detection engine that handles call progress together with machine detection is ViciAMD. Get CPD wrong on a noisy carrier and your reports fill with calls labeled as answers that were actually busy signals or intercept recordings, which makes your contact rate look better than it is and throws off every decision built on top of it. If your answered-call numbers ever look too good for the route you are using, weak call progress detection is usually the first thing to check. This is operational guidance, not legal advice.