A method and system include routing telephone calls from multiple private networks via public lines and trunks in a public switched telephone network (PSTN) to a host switch, at which the connections would begin to run parallel. The host switch routes the telephone calls via a private trunk group to a private facility, such as an electronic tandem network (ETN) node or an asynchronous transfer mode (ATM) switch. If the private trunk group is full or unavailable, the host switch routes the telephone calls over alternate private or public trunk groups and selected carriers.