or on call
1 a : available for use : at the service of <thousands of men at his call > b : ready to respond to a summons or command <a doctor on call >
2 : subject to demand for payment or return without previous notice <money lent at call >
or on call
1 a : available for use : at the service of <thousands of men at his call > b : ready to respond to a summons or command <a doctor on call >
2 : subject to demand for payment or return without previous notice <money lent at call >
Merriam Webster Collegiate English Dictionary. Merriam Webster - Энциклопедический словарь английского языка. 2012