SIP 404 Not Found vs 604 Does Not Exist Anywhere
SIP 404 and 604 both mean the callee was not found, but at different levels of certainty. A 404 means this specific server cannot find the user (they may exist on another server), while a 604 definitively states the user does not exist anywhere in the network.
説明
The user specified in the Request-URI does not exist at the domain. The server has authoritative information that the user does not exist.
このコードが表示される場合
When calling a number or SIP address that does not exist on the server. Different from 480 (user exists but is temporarily unavailable).
修正方法
Verify the SIP URI or phone number. Check if the user is registered on the correct domain. Ensure the domain is correct.
説明
The server has authoritative information that the user indicated in the Request-URI does not exist anywhere. Unlike 404, this is a definitive, global statement.
このコードが表示される場合
When the user definitively does not exist on any server in the network. The server has authoritative knowledge, not just local.
修正方法
The user does not exist. Verify the SIP URI or phone number. Unlike 404, retrying on other servers will not help.
主な違い
404 is server-local — this domain or registrar has no record of the user, but they might exist elsewhere.
604 is a global assertion — the user definitively does not exist anywhere in the network.
404 is a 4xx (client failure); 604 is a 6xx (global failure) that terminates all forked branches.
A proxy receiving 404 may try other routes or domains; a proxy receiving 604 should stop immediately.
604 is authoritative — only the home domain should return it, as only it can definitively say the user does not exist.
使い分け方
Return 404 when a registrar or proxy cannot find the requested user in its local database. Return 604 when the authoritative home domain confirms the user has never existed or has been permanently removed. Use 604 carefully — it tells the entire network to stop looking for this user.