on call

Idioms  

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.

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Example Sentences

See Examples For:

on call

She’s on call for emergencies at all times.

From The Wall Street Journal ● May 13, 2026

Having a good contractor on call is now a must-have for companies building power plants, and they are willing to pay up for them.

From Barron's ● May 4, 2026

It has 40 volunteers who are on call 24/7, and who actively work with local people to prevent crime and increase safety by working with police and other agencies, according to its website.

From BBC ● Apr. 29, 2026

While he worked with Rojas, Battle’s complaint alleges, she required him “to be on call 24/7” and do her personal errands.

From Los Angeles Times ● Mar. 8, 2026

It was late evening, his mother did not like the young doctor who was on call at the medical center in the evenings, and so she drove to Dr. Achufusi’s house.

From "Americanah" by Chimamanda Ngozi Adichie