---
title: "SIP Response Codes"
slug: "sip-response-codes"
description: "This article contains a list of SIP codes that can help you diagnose problems."
updated: 2025-10-23T21:05:11Z
published: 2025-10-23T21:05:11Z
canonical: "support.bcmone.com/sip-response-codes"
---

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

# SIP Response Codes

Some SIP phones and all PBXs display errors or a prompt using the SIP Response codes. This page contains a list of SIP codes that can help you diagnose problems.

### **SIP Responses, class 1**

The 1xx response codes are provisional messages sent indicating call progress.

- 100 Trying
- 180 Ringing
- 181 Call Is Being Forwarded
- 182 Queued
- 183 Session Progress

### **SIP Responses, class 2**

The 2xx class of response codes indicates success.

- 200 OK

### **SIP Responses, class 3**

The 3xx response codes indicate a redirection of the call.

- 300 Multiple Choices
- 301 Moved Permanently
- 302 Moved Temporarily
- 305 Use Proxy
- 380 Alternative Service

### **SIP Responses, class 4**

The 4xx response codes indicate request failures.

- 400 Bad Request
- 401 Unauthorized: Used only by registrars. Proxies should use proxy authorization 407
- 402 Payment Required (Reserved for future use)
- 403 Forbidden
- 403 - Insufficient funds ( often related to the balance on the account or the Fraud control settings for the destination number)
- 404 Not Found: User not found ( Typically the PBX will deliver when an inbound route is not setup for the DID)
- 405 Method Not Allowed
- 406 Not Acceptable
- 407 Proxy Authentication Required
- 408 Request Timeout: Couldn't find the user in time
- 409 Conflict
- 410 Gone: The user existed once but is no longer available
- 413 Request Entity Too Large
- 414 Request-URI Too Long
- 415 Unsupported Media Type
- 416 Unsupported URI Scheme
- 420 Bad Extension: Bad SIP Protocol Extension used, not understood by the server
- 421 Extension Required
- 422 Session Interval Too Small
- 423 Interval Too Brief
- 480 Temporarily Unavailable
- 481 Call/Transaction Does Not Exist
- 482 Loop Detected
- 483 Too Many Hops
- 484 Address Incomplete
- 485 Ambiguous
- 486 Busy Here
- 487 Request Terminated
- 488 Not Acceptable Here
- 491 Request Pending
- 493 Undecipherable: Could not decrypt S/MIME body part

### **SIP Responses, class 5**

The 5xx response codes indicate server failures.

- 500 Server Internal Error
- 501 Not Implemented: The SIP request method is not implemented here
- 502 Bad Gateway
- 503 Service Unavailable
- 504 Server Time-out
- 505 Version Not Supported: The server does not support this version of the SIP protocol
- 513 Message Too Large

### **SIP Responses, class 6**

The 6xxx response codes represent global failures.

- 600 Busy Everywhere
- 603 Decline
- 604 Does Not Exist Anywhere
- 606 Not Acceptable

## Related

- [Perform a Packet Capture/TCP Dump](/perform-a-packet-capturetcp-dump.md)
- [Firewall Requirements for Direct Media Delivery](/firewall-requirements-for-direct-media-delivery.md)