SIP 100 Trying vs 404 Not Found
SIP 100 (Trying) is a 1xx Provisional response, while 404 (Not Found) is a 4xx Client Failure 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, 404 means that the user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
描述
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.
何时出现
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.
如何修复
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
描述
The user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
何时出现
When calling a number or SIP address that does not exist on the server. Different from 480 (user exists but is temporarily unavailable).
如何修复
Verify the SIP URI or phone number. Check if the user is registered on the correct domain. Ensure the domain is correct.
主要区别
100 is a 1xx Provisional response, while 404 is a 4xx Client Failure 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 404: The user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
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 404 when when calling a number or SIP address that does not exist on the server. Different from 480 (user exists but is temporarily unavailable).
何时使用哪个
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 404 (Not Found): Verify the SIP URI or phone number. Check if the user is registered on the correct domain. Ensure the domain is correct.