SIP Trunk Overview

A SIP trunk is a virtual telephone line offered by an Internet Telephony Service Provider (ITSP). Through a SIP trunk, users can make and receive calls over the internet.


Session Initiation Protocol (SIP) is a multimedia communication protocol developed by the Internet Engineering Task Force (IETF), an application-layer control (signaling) protocol for creating, modifying, and terminating sessions with one or more participants.
An Internet Telephony Service Provider (ITSP) is a provider of VoIP telephone service, also known as VoIP service provider.

SIP Trunk Types

Yeastar P-Series Software Edition supports the following SIP trunk types:

SIP Register Trunk
Registration-based SIP trunk that uses username and password for registration with SIP providers.
SIP Peer Trunk
IP-based SIP trunk that uses IP address and port of PBX for authentication.
SIP Account Trunk

SIP Account Trunk is designed for connection between Yeastar P-Series Software Edition and other devices. Yeastar P-Series Software Edition will act as a VoIP account provider, the other device should register this account to connect to Yeastar P-Series Software Edition.

WebRTC Trunk
WebRTC (Web Real-Time Communication) trunk is used to set up WebRTC click-to-call. After you create a WebRTC trunk on the Yeastar P-Series Software Edition, a WebRTC inbound call link will be generated automatically, via which users can make calls to the PBX system.

SIP trunk creation methods

Create a SIP trunk by a template

Yeastar P-Series Software Edition supports leading ITSP across the globe, you can use the pre-configured ITSP templates included in Yeastar P-Series Software Edition to set up a SIP trunk quickly and easily. For more information, see Create a SIP Trunk from a Template.

Note: Check tested and supported ITSP from ITSP partner page.
Create a general SIP trunk
If your ITSP has not undergone an interoperability test by Yeastar, or you want to set up WebRTC Click-to-Call, you can set up a general SIP trunk.
For more information, see the following topics:

SIP Trunk status

Status Description
Registration failed.
  • Authentication failed.
  • Transport type inconsistent.
  • Rejected.
Busy. Maximum channels reached.