433
SIP
433 Anonymity Disallowed
The request has been rejected because the server policy requires caller identification and the request was anonymous.
On this page
When You See This Code
When calling with caller ID suppressed (anonymous) to a server or destination that requires caller identification.
How to Fix
Remove the Privacy header or include proper caller identification. Some networks require valid From header identity.
Specification
Compare With
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
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Frequently Asked Questions
What is SIP 433 Anonymity Disallowed?
The request has been rejected because the server policy requires caller identification and the request was anonymous.
When do you see SIP 433 Anonymity Disallowed?
When calling with caller ID suppressed (anonymous) to a server or destination that requires caller identification.
How to fix SIP 433 Anonymity Disallowed?
Remove the Privacy header or include proper caller identification. Some networks require valid From header identity.