OSI (Open Systems Interconnection)

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OSI (Open Systems Interconnection)[1]

A 7-layer hierarchical reference model structure developed by the International Standards Organization for defining, specifying, and relating communications protocols; not a standard or a protocol;

Layer Description

(7) Application: provides interface with network users,

(6) Presentation: performs format and code conversion,

(5) Session: manages connections for application programs,

(4) Transport: ensures end-to-end delivery,

(3) Network: handles network addressing and routing,

(2) Data Link: performs local addressing and error detection and

(1) Physical: includes physical signaling and interfaces.

OSI (Open Systems Interconnection)[2]

A conceptual model that describes how computer systems communicate with each other across LANs and WANs. While it is a defined standard (ISO 7498-1), it is more commonly used as a reference architecture.

A conceptual reference model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology.

Relevant NENA Documents
Note: To find and download the document, copy the document number (like NENA-STA-010) from below and search the NENA Standards and Documents page.


  1. NENA-STA-010.3 (DRAFT) NENA i3 Standard for Next Generation 9-1-1 (DRAFT) Download
  2. NENA-INF-016, NENA Emergency Services IP Network Design (ESIND) Information Document

NENA-INF-003, NENA Potential Points of Demarcation in NG9-1-1 Networks Information Document

External References


ISO/IEC 7498-1:1994 Information technology — Open Systems Interconnection — Basic Reference Model: The Basic Model