on call

1. Available if summoned, as in Medical residents are required to be on call at least three nights a week. This expression originated as at call in the late 1500s. Also see at someone's beck and call.

Example Sentences

Dr. Elizabeth Hudson, the regional chief of infectious diseases at Kaiser Permanente Southern California, said she received many calls related to outpatient cases of COVID-19 while on call over the Labor Day weekend.

From Los Angeles Times

Alex Freeland started the third with his first career triple before scoring on Call’s two-out, two-strike single to left while singles by Betts and Freeman, a scoring fly ball from Michael Conforto and an RBI double from Freeland pushed the led to 7-1.

From Los Angeles Times

School police — though diminished in numbers due to staffing cuts — are to patrol sensitive areas and are on call to move quickly to where situations arise.

From Los Angeles Times

Kirk, who works by day delivering babies as the county’s only OB-GYN, said he wasn’t drinking that night because he was on call.

From Los Angeles Times

Dr Pitt, who was on call through the night into Christmas morning, was asked what state Dr Upton was in.

From BBC