SIP 100 Trying vs 180 Ringing
Both SIP 100 (Trying) and 180 (Ringing) belong to the 1xx Provisional category. 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. Meanwhile, 180 means 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.
Description
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.
Quand vous le voyez
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.
Comment résoudre
No fix needed — this is normal call setup behavior. If stuck on 100 Trying for too long, check network connectivity and proxy configuration.
Description
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.
Quand vous le voyez
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
Comment résoudre
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.
Différences clés
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 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.
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 180 when during call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
Quand utiliser lequel
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 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.