SIP 180 Ringing vs 305 Use Proxy
SIP 180 (Ringing) is a 1xx Provisional response, while 305 (Use Proxy) is a 3xx Redirection 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, 305 means that the requested resource must be accessed through the proxy given by the Contact header field.
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.
When You See It
During call setup when the callee's phone is ringing. You should hear a ringback tone after receiving this response.
How to Fix
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.
Description
The requested resource must be accessed through the proxy given by the Contact header field.
When You See It
When the request must be routed through a specific outbound proxy server.
How to Fix
Resend the request through the proxy specified in the Contact header of this response.
Key Differences
180 is a 1xx Provisional response, while 305 is a 3xx Redirection 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 305: The requested resource must be accessed through the proxy given by the Contact header field.
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 305 when when the request must be routed through a specific outbound proxy server.
When to Use Which
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 305 (Use Proxy): Resend the request through the proxy specified in the Contact header of this response.