SIP 200 OK vs 423 Interval Too Brief
SIP 200 (OK) is a 2xx Success response, while 423 (Interval Too Brief) 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, 423 means that the expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
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 expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
When You See It
When a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
How to Fix
Increase the Expires header value to at least the Min-Expires value from the response.
Key Differences
200 is a 2xx Success response, while 423 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 423: The expiration time in the request is too short. The response contains a Min-Expires header indicating the minimum allowed value.
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 423 when when a REGISTER or SUBSCRIBE request has an Expires value that is below the server's minimum. Common with aggressive keep-alive timers.
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 423 (Interval Too Brief): Increase the Expires header value to at least the Min-Expires value from the response.