This counter tallies the number of call setup attempts, both successful and unsuccessful, detected on this interface. Because it counts every incoming SETUP message regardless of outcome, comparing its growth against ciscoatmSigInEstabls, the count of calls that actually completed, gives the real incoming call success rate for this signaling interface. This counter rising to 1000 while ciscoatmSigInEstabls only reaches 600 over the same period means 40 percent of incoming call attempts on this interface are failing for one reason or another.