The term "most on-call" can be substituted with various synonyms to convey the same meaning. Some of the synonyms that can be used instead of "most on-call" include "frequently available," "regularly responsive," "always at the ready," and "readily accessible." All these synonyms imply that the person is easily reachable and available to attend to any urgent matters that require immediate attention. For instance, a doctor might be considered to be "frequently available" or "always at the ready" if they are always on-call to attend to emergencies. Similarly, a technician might be regarded as readily accessible if they can be reached at any time of day or night.