Abstract: An inexpensive and flexible method and apparatus for inter-working in circuit, packet and circuit packet networks between one or more access protocols and one or more destination protocols. By consolidating the inter-working logic in an Abstracted Common Call Control Inter-working Function (ACCCIF) that operates on abstracted signals and events, configuration and maintenance are simplified. At the same time, extending the invention by adding, updating or deleting protocols may be achieved quickly and consistently while the need to buy additional equipment in order to extend services is minimized. A preferred embodiment utilizes protocol engines and is implemented as a finite state machine.