Release & Upgrade
Release Notice for RMS V2.5.24
Release Notice for UMSV1.1.41
Finder v1.0.9
OM50G V177 P2.2
OM20G V177 P2.2
NeeHau Client V2.0.0.23 (with OM20/20G/50/50G)
OM20G V177 P2
OM50G V177 P2
OM80E V177 P3

What is the purpose of SIP in VoIP?
The Difference Between PBX And PSTN
What Is The Meaning Of Hosted Pbx ?
How Do You Choose An IP PBX For Your Small Business?
How To Install New Rock OM20 IPPBX-OM20g Installation
Why are PBX's Becoming VoIP Based?
What's the Meaning of PBX And How does a PBX system work?
How Is Ip Pbx Different From Traditional PBX?
How does a hotel phone system work?
What is PSTN gateway?
Is VoIP Phone worth it for a small business?
The Difference Between A Ip Phone And A Voip Phone
Can you use your old phone with VoIP?
What Is The Sip Response Code?
What is VoIP Server And How a VOIP Server Works
What is SIP 500 error
What Is Voip Gateway
Ip-pbx Vs Voip Gateway
Best PBX Phone System Features for Businesses
How to Setup a VoIP System in Office
PBX Software Features
Traditional IP PBX configurations
How to choose business telephony system
IP PBX vs. Traditional PBX
PBX IP PBX and VoIP technology Advantages
Guide to Business VOIP PBX
PBX phone systems for small businesses
How Does a SIP Gateway Work?
SIP, VOIP & IP Phones
VoIP Phone Systems - Create the Perfect Business Phone System
What Is a PBX Phone System
How much business Phone System
What is a PBX System
Why use VOIP
What are the advantages of VoIP services
FXO/FXS Gateways
Which Voip Phone System Is Right for Your Business
How do I choose a VoIP provider
Flexible Hotel Phone Systems From New Rock
How Can VoIP Help Hotels Cut Cost
Hospitality Technology Solutions
Modern phones for hotel rooms
VoIP to the hospitality industry
Hotel phone system improves hotel service experience
Why is a Hotel Phone System Important
How Hotel Phone Systems
The Importance Of Using Hotel Phone System
Hotel VOIP telephone system
Small Hotel Phone System for up to 50 Rooms
How Hotels Use a PBX Phone System

Application Notes
How to Integrate MX Gateway with OM IP-PBX
Interconnect Two PBXs with FXO Gateways
Interconnect Two or More Extension Lines with FXS Gateways
Connecting MX100G-S SIP-ISDN Gateway to Elastix
Connecting MX100G-S SIP-ISDN Gateway to Asterisk
Expanding PBX Extensions to Remote Sites through IP Network
Multi-site Configuration for Gateways with Analog PBX
How to Troubleshoot Caller ID Detection Issues on FXO Port
Security Configuration Guide for New Rock OM Series IP-PBX
Connecting FXO Gateway to Asterisk
Connecting FXO Gateway to Elastix
Tie Trunk Configuration for OM with Elastix

Training Materials
What is VoIP gateway?
What’s the Difference between VoIP Gateway and SIP Trunk?
Smart Switchboard Introduces Exclusive Premium Customer Services
What's the Difference Between VoIP Gateway and ATA?
What's the Difference Between VoIP gateway and SBC?
New Rock’s New Gateway Security measures
Global VoIP Gateway Service Provider
How to Setup VoIP Gateway - A Complete Installation Guide
What is HX&MX VoIP Gateway Default Password?
Auto Provisioning
Six Practices for Audio Security
“PSTN failover” - Strong Support for High-availability IP Audio Communications
New Rock IP-PBX: Your All-In-One IP Office Telephony System
Connecting E1/T1-Based PBX to IP Telephony Networks
Popular IP-PBX Features Favored by Highly Efficient Officers
Five-star Customer Services
Top Three Advantages of Gateways with Imbedded VPN Clients
Low-Cost, High-Quality Gateway
Smart FoIP
Two Typical Applications for Telephone Networks
IPv6’s Top Three Advantages in VoIP Applications
MX100G-S SIP-ISDN Trunking Gateway Training
MX Series VoIP Gateway Training


Installation & Maintenance
OM SIP Trunk Configuration Documentation
NAT Traversal Service---Configuration video
User Guide for Finder V1.0.9
IP-PBX Installation (Video)
OM20G&OM50G Quick Installation Guide
OM80E Quick Start Guide
OM200G Quick Start Guide
OM500 Quick Installation Guide
HX4G&MX8G Quick Reference Guide
MX60E Quick Installation Guide
MX120G Quick Installation Guide
MX100G-S Quick Start Guide
SX3000 Quick Installation Guide
PT2400 Quick Installation Guide
PT4800 Quick Installation Guide

Marketing Materials

What Is The Sip Response Code?
Update Time:2021-08-30 14:33:25 Browse Times:855 Amount Downloads:1

The Session Initiation Protocol (SIP) is a signalling protocol used for controlling communication sessions such as Voice over IP telephone calls. SIP is based on request/response transactions, in a similar manner to the Hypertext Transfer Protocol (HTTP). Each transaction consists of a SIP request (which will be one of several request methods), and at least one response. In short,SIP is a call and response protocol. If you send a message, you’ll get a response, and in some cases, you might get multiple responses.

What Is The Sip Response Code?

SIP requests and responses may be generated by any SIP user agent; user agents are divided into clients (UACs), which initiate requests, and servers (UASes), which respond to them.[1]:§8 A single user agent may act as both UAC and UAS for different transactions:[1]:p26 for example, a SIP phone is a user agent that will be a UAC when making a call, and a UAS when receiving one. Additionally, some devices will act as both UAC and UAS for a single transaction; these are called Back-to-Back User Agents (B2BUAs).From a more technical standpoint, a SIP response will contain information sent by a User Agent Server (UAS) to a User Agent Client (UAC).

These responses are designed to help and inform. Each code consists of three digits, with the first digit of the code placing the response into one of six class types:

1xx is ‘Informational’

2xx is ‘Success’

3xx is a ‘Redirection’

4xx is a ‘Client Error’

5xx is a ‘Server Error’

6xx is a ‘Global Failure’

These class types can also be broken into two categories: code 1xx is known as a ‘Provisional’ code, and codes 2xx-6xx are referred to as ‘Final’ codes.

For an easy way to remember this distinction - a ‘Provisional’ code can be sent up until the point of establishment, or before you’ve made a connection. The ‘Final’ codes will be sent to confirm whether you’ve successfully made a connection or not (error, redirection, failure).

List of SIP response codes

Each code is accompanied by an explanatory description string, so thankfully, you don’t necessarily need to remember all the codes and what they mean. It might help to know what action to take based on what you receive back from the UAS. Here are the most common types of SIP response codes that you’re likely to encounter, and their meanings.

1xx - Informational

As mentioned earlier, a 1xx SIP response code can be sent at any time while a connection is being established. Some common 1xx codes are:

100 - Trying

The request has been received, and an unspecified action is being taken on behalf of the call.

180 - Ringing

An invite has been received by the user agent and it is now trying to alert the user.

181 - Call is Being Forwarded

Indicates that the call is being forwarded to another endpoint.

183 - Session Progress

This code is used to give information about the progress of a call.

199 - Early Dialog Terminated

Indicates to upstream SIP entities that an early dialog has been terminated.

2xx - Success

The 2xx response codes are used to indicate that a SIP request has been successfully received, understood, and accepted. You’ll typically see the following versions:

200 - Ok

The request has succeeded.

202 - Accepted

The UAS has received and understood the request, but it may not have been authorized or processed by the server.

204 - No Notification

The request was successful, but the response will not be received.

3xx - Redirection

These notify the UAC on redirections and of the different routes available to get to the UAS. Commonly received examples include:

300 - Multiple Choices

The request address returned several choices, each with their own specific locations. In this case, the UA can select a preferred endpoint to redirect the request to that specific location.

301 - Moved Permanently

The user can no longer be found at the address used in the request. A new address will be given in the contact header field, which can be retried by the requesting client. The new address should be saved and used in all future invite requests.

302 - Moved Temporarily

A new address will be given in the contact header field, which can be retried by the requesting client. This address should not be saved for future invite requests.

305 - Use Proxy

A proxy must be used to access the required destination. The specified proxy will be displayed in the contact field.

380 - Alternate Service

The call failed, but the message body details alternatives.

4xx - Client Error

The 4xx response codes indicate that something went wrong while processing the message, and the request cannot be fulfilled. There are quite a few of them, including:

400 - Bad Request

The request could not be understood.

401 - Not Authorized

The request requires user authentication.

404 - Not Found

The server has definitive information that the user does not exist at that particular domain.

407 - Proxy Authentication Required

This code is similar to the 401 - Not Authorized code, but in this case, the client must authenticate itself with the proxy.

408 - Request Timeout

The server could not produce a response within a suitable time frame.

415 - Unsupported Media Type

The server is refusing to service the request because the message body is in a format not supported by the server for the particular request method.

5xx - Server Error

5xx responses relate to server error issues and are mostly generated by the likes of proxy servers, location servers, and redirect servers. You’ll be familiar with some of these:

500 - Server Internal Error

The server was prevented from fulfilling the request by an unexpected condition.

501- Not Implemented

The functionality required to fulfill the request is not supported by the server.

502 - Bad Gateway

When attempting to fulfill the request, the server received an invalid response from a downstream server.

503 - Service Unavailable

Temporary overloading or maintenance of the server means it is currently unable to process the request. The client should attempt to forward the request to another server.

504 - Server Time-Out

When attempting to process the request, the server did not receive a timely response form the external server.

6xx - Global Error

Finally, the 6xx response codes relate to Global Error issues. They include:

600 - Busy Everywhere

The callee’s end system was contacted successfully but the callee is busy.

603 - Decline

The callee’s end system was successfully contacted but the user does not wish to or cannot participate.

604 - Does Not Exist Anywhere

There is information that the user indicated in the request URI does not exist.

606 - Not Acceptable

The user wishes to communicate but they cannot adequately support the session described.

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