This read-only Integer32 (0..2147483647) reports the cell transfer delay of UBR (Unspecified Bit Rate) service on the interface, a measure of the end-to-end latency cells of that class currently experience. An administrator watches this to detect when UBR (Unspecified Bit Rate) traffic is experiencing elevated latency, which matters most for delay-sensitive classes like CBR and real-time VBR carrying voice or video. For example, a rising cwspLoadCtdUbr value on a trunk correlates with reports of quality degradation on UBR (Unspecified Bit Rate)-carried applications, prompting an engineer to check for congestion on that interface.