SIP 200 OK vs 401 Unauthorized
SIP 200 (OK) is a 2xx Success response, while 401 (Unauthorized) is a 4xx Client Failure response. 200 indicates that the request has succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully. In contrast, 401 means that the request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
Description
The request has succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully.
When You See It
When a call is answered (INVITE 200 OK), a registration succeeds (REGISTER 200 OK), or a subscription is accepted (SUBSCRIBE 200 OK).
How to Fix
No fix needed — this is a success response. The caller should send an ACK to complete the three-way handshake for INVITE transactions.
Description
The request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
When You See It
When making a request that requires Digest authentication. Common for REGISTER and INVITE requests to authenticated SIP trunks.
How to Fix
Resend the request with proper Authorization header containing valid credentials (Digest authentication).
Key Differences
200 is a 2xx Success response, while 401 is a 4xx Client Failure response.
SIP 200: The request has succeeded. For INVITE, the call has been answered. For other methods, the action has been completed successfully.
SIP 401: The request requires user authentication. The response includes a WWW-Authenticate header with a challenge for the realm.
You encounter 200 when when a call is answered (INVITE 200 OK), a registration succeeds (REGISTER 200 OK), or a subscription is accepted (SUBSCRIBE 200 OK).
You encounter 401 when when making a request that requires Digest authentication. Common for REGISTER and INVITE requests to authenticated SIP trunks.
When to Use Which
For 200 (OK): No fix needed — this is a success response. The caller should send an ACK to complete the three-way handshake for INVITE transactions. For 401 (Unauthorized): Resend the request with proper Authorization header containing valid credentials (Digest authentication).