SIP 300 Multiple Choices vs 486 Busy Here
SIP 300 (Multiple Choices) is a 3xx Redirection response, while 486 (Busy Here) is a 4xx Client 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, 486 means that the callee's end system was contacted successfully but the callee is currently not willing or able to take additional calls at this end system.
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 currently not willing or able to take additional calls at this end system.
When You See It
When the callee is already on a call and does not have call waiting. The user explicitly rejected the call, or all lines are in use.
How to Fix
Wait and try again later. The callee may become available when their current call ends. Consider leaving a voicemail if available.
Key Differences
300 is a 3xx Redirection response, while 486 is a 4xx Client 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 486: The callee's end system was contacted successfully but the callee is currently not willing or able to take additional calls at this end system.
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 486 when when the callee is already on a call and does not have call waiting. The user explicitly rejected the call, or all lines are in use.
When to Use Which
For 300 (Multiple Choices): Select one of the provided Contact addresses and resend the request to that specific URI. For 486 (Busy Here): Wait and try again later. The callee may become available when their current call ends. Consider leaving a voicemail if available.