What is required to enable the train to pass a call-on signal?

To enable a train to pass a call-on signal, the correct requirement is to be in release mode. This mode allows the train to proceed past a signal that would typically indicate a stop condition, such as a red signal, under specific circumstances. Release mode ensures the safe and controlled movement of the train by allowing engineers to pass the signal provided they have received the necessary clearance or authority to do so.

In this context, high-speed operation does not pertain to passing a call-on signal because speed must be controlled, especially in potentially hazardous areas. Manual operation generally refers to the direct control of the train, but it does not specifically govern the passing of signals. Lastly, MATC (Multiple Aspect Train Control) mode pertains to operational mode features that allow trains to receive signals digitally, but it is not the specific action required to pass a call-on signal in the manner that release mode is designed for.