at someone's beck and call

at someone's beck and call

Required to comply with someone's requests or commands, as in The boss expects the entire staff to be at his beck and call. The noun beck, now obsolete except in this idiom, meant "a gesture or signal of command, such as a nod or hand movement," whereas call signifies "a vocal summons." Also see dance attendance on.
See also: and, beck, call

at someone's beck and call

always having to be ready to obey someone's orders immediately.
Beck in the sense of ‘a significant gesture of command’ comes from the verb beck , a shortened form of beckon . It is now found mainly in this phrase.
See also: and, beck, call