From NENA Knowledge Base

“i3” refers to the NG9-1-1 system architecture defined by NENA, which standardizes the structure and design of Functional Elements making up the set of software services, databases, network elements and interfaces needed to process multi-media emergency calls and data for NG9-1-1. See NGCS (Next Generation 9-1-1 Core Services), ESInet (Emergency Services IP Network), and NG9‑1‑1 (Next Generation 9‑1‑1).

Relevant NENA Documents