---
title: "8x8 SIP trunking interface specification"
slug: "8x8-sip-trunking-interface-specification"
updated: 2026-09-01T13:14:24Z
published: 2026-09-01T13:14:24Z
canonical: "help.8x8.com/8x8-sip-trunking-interface-specification"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.8x8.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 8x8 SIP trunking interface specification

## Overview

The 8x8 SIP trunking interface specification defines the requirements for interoperability between a SIP trunking client and the 8x8 SIP trunking interface and services. It covers the supported SIP standards, methods, and headers; supported media codecs and transport protocols; authentication requirements; Request-URI, To, and From header formatting; e911 support; and sample SIP call flows for outbound and inbound calls.

Use this specification when configuring a PBX, session border controller, or other SIP trunking client to connect with the 8x8 SIP trunking service, or when troubleshooting SIP trunking interoperability issues.

## Download

This PDF contains the full 8x8 SIP trunking interface specification, including supported SIP standards, headers, and transport protocols, media codec and NAT traversal requirements, authentication details, e911 support, and sample outbound and inbound call flows. Download this file to get the complete technical reference for configuring and troubleshooting your SIP trunking connection to 8x8.

[8x8 SIP Trunking Interface Specification](https://cdn.us.document360.io/e3a59e39-abd3-4423-964c-0a4008dc5673/Images/Documentation/8x8%20SIP_Interface_Spec_trunk_ver.2.0.pdf?sv=2026-02-06&spr=https&st=2026-11-01T07%3A03%3A51Z&se=2026-11-01T08%3A03%3A51Z&sr=c&sp=r&sig=Egg%2BqQ%2FIHwabzupPjP9I4lCXNo%2F%2FIjhEujBS9uzlEf8%3D)