This read-only enumerated INTEGER (none, inactive, activating, activated, activatedCpeDetected) reports the internal IDSL training state of the port, with activatedCpeDetected meaning the line has trained and a CPE has been detected on the far end. An admin uses it to distinguish a line that simply hasn't been plugged in (inactive) from one that is actively failing to train (activating stuck) or one that is fully up (activatedCpeDetected). For example, a port stuck in activating for several minutes without ever reaching activatedCpeDetected suggests the CPE at the customer's end isn't responding.