This read-only counter tracks the number of received HDLC frames that exceeded the maximum permissible frame size and were therefore presumably discarded or flagged as errors. Admins watch this counter to detect a misbehaving far-end device or a framing or MTU mismatch on the link. For example, a session showing a steadily increasing cmmOversizeFrames count would suggest the remote end is sending frames larger than this modem's HDLC implementation allows, likely causing data loss.