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

With lengthy rosters of witnesses on call, attorneys have confronted difficult choices about how to juggle their hired experts with family members, doctors and testimony from Sanderson and Paltrow themselves.

From Seattle Times

They also detailed how the scheduling system, insufficient wages, and expensive benefits forced many Starbucks employees to work second jobs—which was all the more difficult because the company required them to be on call even when they weren’t working.

From Slate

In the second week of trial, it’s clear that both sides have spared little expense to ensure they have a roster of expert witnesses on call in case needed.

From Seattle Times

Once organs are removed from the body, it is vital that they move to their new hosts quickly, which requires better coordination among surgeons and hospitals so they are on call to operate.

From Washington Post

The lawsuit states that those on call that day “failed to summon an ambulance,” despite Mitchell’s “serious need for immediate emergency medical treatment.”

From Washington Post