Abstract: This invention relates to the minimizing of call set-up time for calls requiring the use of service circuits provided from a separate switching system, such as a service circuit node (SCN). Groups of semi-permanent circuits through a public switched telephone network (PSTN) are allocated to each of the switching systems served by the SCN. Thus, whenever a switching system has a call that requires the use of a service circuit housed in the SCN, the connection is already established. Traffic is controlled by limiting in the size of the semi-permanent circuit groups, but these groups can be made larger or smaller, up to some overall total for the SCN, as traffic to each switching system changes. Advantageously, this arrangement permits efficient use of a large group of service circuits at the SCN, while minimizing the total call set-up time.