SIP 300 Multiple Choices vs 600 Busy Everywhere
SIP 300 (Multiple Choices) is a 3xx Redirection response, while 600 (Busy Everywhere) is a 6xx Global Failure response. 300 indicates that the address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint. In contrast, 600 means that the callee's end system was contacted successfully but the callee is busy and does not wish to take the call at this time. Unlike 486 (Busy Here), this is a definitive response.
Description
The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
When You See It
When a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
How to Fix
Select one of the provided Contact addresses and resend the request to that specific URI.
Description
The callee's end system was contacted successfully but the callee is busy and does not wish to take the call at this time. Unlike 486 (Busy Here), this is a definitive response.
When You See It
When the callee has rejected the call on all devices. No other endpoints should be tried. The user is universally busy.
How to Fix
Wait and try again later. No alternative contact points exist. The callee must become available on their own.
Key Differences
300 is a 3xx Redirection response, while 600 is a 6xx Global Failure response.
SIP 300: The address in the request resolved to several choices, each with its own location. The user or UA can select a preferred communication endpoint.
SIP 600: The callee's end system was contacted successfully but the callee is busy and does not wish to take the call at this time. Unlike 486 (Busy Here), this is a definitive response.
You encounter 300 when when a user has multiple registered devices or contact addresses and the server cannot determine which one to use.
You encounter 600 when when the callee has rejected the call on all devices. No other endpoints should be tried. The user is universally busy.
When to Use Which
For 300 (Multiple Choices): Select one of the provided Contact addresses and resend the request to that specific URI. For 600 (Busy Everywhere): Wait and try again later. No alternative contact points exist. The callee must become available on their own.