SIP 100 Trying vs 380 Alternative Service
SIP 100 (Trying) is a 1xx Provisional response, while 380 (Alternative Service) is a 3xx Redirection response. 100 indicates that the request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses. In contrast, 380 means that the call was not successful but alternative services are possible. The response body contains a description of alternative services.
Descrição
The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
Quando você o vê
Immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
Como corrigir
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
Descrição
The call was not successful but alternative services are possible. The response body contains a description of alternative services.
Quando você o vê
Rarely seen in practice. Indicates that the request cannot be fulfilled as-is but the user may be reached via an alternative method.
Como corrigir
Check the response body for alternative service descriptions and attempt to reach the user through those channels.
Diferenças principais
100 is a 1xx Provisional response, while 380 is a 3xx Redirection response.
SIP 100: The request has been received by the next-hop server and an unspecified action is being taken to process it. The UAC should expect additional responses.
SIP 380: The call was not successful but alternative services are possible. The response body contains a description of alternative services.
You encounter 100 when immediately after sending an INVITE. The proxy has received the call and is searching for the callee. This is the SIP equivalent of a dial tone.
You encounter 380 when rarely seen in practice. Indicates that the request cannot be fulfilled as-is but the user may be reached via an alternative method.
Quando usar qual
For 100 (Trying): No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration. For 380 (Alternative Service): Check the response body for alternative service descriptions and attempt to reach the user through those channels.