https://app.knowbase.one/vault/rfc/docid/5583
RFC0511: Enterprise phone service to NIC from ARPANET sites
ARPA Network Information Center Jeanne North Stanford Research Institute SRI NIC Menlo Park, California 94025 23 May 1973 RFC 511 NIC 16442 Updates NIC 7554, NIC 7732 Enterprise Phone Service to NIC ...