An exemplary method includes network elements associated with distinct network domains exchanging signaling and media border processing information by way of a secure packet-switched connection between the network elements, exchanging service policy information by way of the secure packet-switched connection, peering a session associated with a first service type between the distinct network domains by way of a packet-switched network-to-network interconnection interface (“NNII”) in accordance with the exchanged signaling and media border processing information, peering another session associated with a second service type between the distinct network domains by way of the packet-switched NNII in accordance with the exchanged signaling and media border processing information, enforcing a first performance threshold specified by the service policy information for peering the session associated with the first service type, and enforcing a second performance threshold specified by the service policy information for peering the other session associated with the second service type.