International priority calling system

A telephone call initiated from a first network and directed to a second network at which network resources are temporarily unavailable to route and/or switch that call, is completed by a) estimating the anticipated time before these resources can become available, b) offering the caller the option of being called back, based on that estimation, c) calling back the caller when network resources are expected to become available, d) establishing a connection from the first network to the called party at the second network, and e) merging the two calls.