SIP 180 Ringing vs 603 Decline
SIP 180 (Ringing) is a 1xx Provisional response, while 603 (Decline) is a 6xx Global Failure 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, 603 means that the callee's machine was contacted successfully but the user explicitly does not wish to or cannot participate. Unlike 600, this may be because the callee doesn't want to communicate, not necessarily
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 callee's machine was contacted successfully but the user explicitly does not wish to or cannot participate. Unlike 600, this may be because the callee doesn't want to communicate, not necessarily because they're busy.
When You See It
When the callee explicitly declines the call. This is an active rejection, not a busy or unavailable state.
How to Fix
The callee has declined. Respect their decision. Consider alternative communication methods (email, messaging).
Key Differences
180 is a 1xx Provisional response, while 603 is a 6xx Global Failure 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 603: The callee's machine was contacted successfully but the user explicitly does not wish to or cannot participate. Unlike 600, this may be because the callee doesn't want to communicate, not necessarily
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 603 when when the callee explicitly declines the call. This is an active rejection, not a busy or unavailable state.
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 603 (Decline): The callee has declined. Respect their decision. Consider alternative communication methods (email, messaging).