1. A method comprising: exchanging, by at least one network element of a first network domain, signaling and media border processing information with at least one network element of a second network domain by way of a secure packet-switched connection between the at least one network element of the first network domain and the at least one network element of the second network domain; exchanging, by the at least one network element of a first network domain, service policy information with the at least one network element of the second network domain by way of the secure packet-switched connection; peering, by the at least one network element of the first network domain, at least one session associated with a first service type between the first network domain and the second network domain by way of a packet-switched network-to-network interconnection interface in accordance with the exchanged signaling and media border processing information; peering, by the at least one network element of the first network domain, at least one other session associated with a second service type between the first network domain and the second network domain by way of the packet-switched network-to-network interconnection interface in accordance with the exchanged signaling and media border processing information; enforcing, by the at least one network element of the first network domain, a first performance threshold specified by the service policy information for the peering of the at least one session associated with the first service type; and enforcing, by the at least one network element of the first network domain, a second performance threshold specified by the service policy information for the peering of the at least one other session associated with the second service type.