The rate at which new call attempts are sent or received on a trunk or network, used both as a capacity limit and as a fraud and robocall signal.
CPS measures how quickly calls are being set up, regardless of how long they last. It is distinct from concurrent calls, which counts how many calls are active at once. Providers usually set CPS limits on each trunk to protect their switches and upstream routes from overload. Upstream carriers impose their own CPS limits as well, and exceeding them can cause rejected calls or damaged relationships.
Ordinary business traffic rarely needs a high CPS. Auto-dialers, robocall campaigns, and some fraud attacks, on the other hand, generate bursts of call attempts far faster than humans can dial. A sudden jump in CPS from a customer whose traffic normally trickles in is often the first visible sign of a problem.
Setting CPS limits that match each customer's legitimate use case, and alerting when traffic presses against them, provides a simple and effective control. Limits should be reviewed when a customer requests an increase, since that request is itself a useful moment to ask what has changed in their business.
Why it matters to carriers
CPS limits are one of the few controls that work instantly and do not depend on knowing anything about the content of the calls. Right-sizing them per customer contains toll fraud and robocall bursts, while monitoring CPS trends helps you spot customers whose traffic no longer matches what they described during onboarding.