SIP 180 Ringing vs 204 No Notification
SIP 180 (Ringing) is a 1xx Provisional response, while 204 (No Notification) is a 2xx Success response. 180 indicates that the UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end. In contrast, 204 means that the request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
Descrição
The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
Quando você o vê
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
Como corrigir
No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings.
Descrição
The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
Quando você o vê
When subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
Como corrigir
No fix needed. The subscription was accepted but there is no state change to notify about yet.
Diferenças principais
180 is a 1xx Provisional response, while 204 is a 2xx Success response.
SIP 180: The UA receiving the INVITE is trying to alert the user. This response is used to initiate local ringback tone at the caller's end.
SIP 204: The request was successful but the server has decided not to send a NOTIFY for this SUBSCRIBE request.
You encounter 180 when during call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
You encounter 204 when when subscribing to event packages that may not generate immediate notifications, such as dialog or presence packages.
Quando usar qual
For 180 (Ringing): No fix needed — the callee's device is ringing. If the call never connects after ringing, check the callee's device or call forwarding settings. For 204 (No Notification): No fix needed. The subscription was accepted but there is no state change to notify about yet.