To be at someone’s “beck and call” means to be standing by and prepared to immediately respond to that person’s needs.
The expression comes from the rules of servitude, when a beck was a silent signal, such as a nod of the head or a hand gesture, used to summon a servant.
If this subtlety didn’t work, then the master or mistress would resort to a call.
This meant they had used a beck and a call to get the domestic’s attention.
