A controller that monitors usage status of trunk lines associated with a switch that operates to handle call connections between calling devices and called devices on trunk lines associated therewith. An exemplary controller comprises N call application nodes capable of executing trunk idle list server applications that allocate ones of the trunk lines to the call connections, wherein a first trunk idle list server application is executed on a first call application node and is associated with a second trunk idle list server application executed on a separate second call application node. The first and second trunk idle list server applications thereby form a first load sharing group server application, that operates to receive a trunk line allocation request from a call process being executed within the switch and selects either the first or second trunk idle list server application to allocate a trunk line to a call connection associated with the trunk line allocation request according to a load distribution algorithm.