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ProtocolCodes
180
SIP

180 Ringing

The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.

On this page

When You See This Code

During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.

How to Fix

No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.

Specification

View RFC / Specification →

Compare With

100 Trying 181 Call Is Being Forwarded 182 Queued 183 Session Progress 199 Early Dialog Terminated 200 OK 202 Accepted 204 No Notification 300 Multiple Choices 301 Moved Permanently 302 Moved Temporarily 305 Use Proxy

Guides

401 Unauthorized vs 403 Forbidden: When to Use Each Security & Authentication
SIP Response Codes: Understanding VoIP Call Flow Real-Time Protocols
SIP Call Flow: Understanding Session Setup Real-Time Protocols
WebRTC Signaling with SIP and WebSocket Real-Time Protocols
RFC 3261: SIP Protocol Deep Dive Protocol Deep Dives
TLS 1.3: Faster, Simpler, More Secure Protocol Deep Dives

Specifications

RFC 3261 SIP: Session Initiation Protocol
RFC 3262 Reliability of Provisional Responses in SIP

Glossary

Status Code Request Method (HTTP Verb) TLS Handshake Authentication TCP/IP Port Number NAT (Network Address Translation) Socket Request-Response Model RFC (Request for Comments) Connection-Oriented Full-Duplex SRV Record SIP Dialog Signaling SIP Registrar STUN (Session Traversal Utilities for NAT) TURN (Traversal Using Relays around NAT) SDP (Session Description Protocol) SIP INVITE SIP Proxy Server SIP Redirect Server SIP Transaction SIP User Agent SIP Trunk RTP (Real-time Transport Protocol) SRTP (Secure Real-time Transport Protocol) SIP ACK SIP BYE SIP CANCEL SIP OPTIONS SIP SUBSCRIBE/NOTIFY B2BUA (Back-to-Back User Agent) SBC (Session Border Controller) Codec Negotiation SIP Response Classes VoIP (Voice over IP) Presence (SIP) PBX (Private Branch Exchange) MFA (Multi-Factor Authentication) TLS Versions

Frequently Asked Questions

What is SIP 180 Ringing?

The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.

When do you see SIP 180 Ringing?

During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.

How to fix SIP 180 Ringing?

No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.