This Recommendation defines the interface and the procedures applicable for the purpose of providing a gateway function in a PSPDN to a private PSDN. This Recommendation has been developed in direct response to a market demand for the PSPDN to provide a mechanism for interconnection between a private and public network on a peer-to-peer basis that does not rely on the provisioning of X.75 STEs in both the private PSDN and the PSPDN. This Recommendation will permit private networks to create Virtual Private Networks (VPNs) across the PSPDNs resources and participate in other features of a PSPDN not available in the private network such as ICUGs.