This counter reports the cumulative time this T1 interface has spent receiving a 'yellow alarm,' which the far end signals by zeroing bit 2 of 256 consecutive channels in D4 framing, or by repeating 00FF patterns in FDL framing, to indicate it can't receive a valid signal from this end. Because a yellow alarm reflects a problem the remote end sees on its receive path, admins use it to tell whether a T1 fault lies on the transmit side toward the far end rather than on their own receive path. If dsx1ExtCfgT1RxYellowAlarm starts climbing, an admin would check the outbound transmit signal quality toward the remote T1 equipment rather than assume a local receive fault.