This counts LMI frames received by the DTE side that contained protocol errors, malformed or non-conformant LMI messages, rather than normal status or poll traffic. An admin treats a climbing lportDTEInErrorFrames as a sign of LMI incompatibility or corruption between this device and its peer, distinct from physical-layer errors tracked elsewhere. For example, a jump in this counter right after a carrier or CPE firmware upgrade would point the admin toward an LMI protocol-version mismatch as the likely cause.