While lecturing on SIP response codes, I’ve had several students ask for an explanation of the case usage for a ‘603 Decline’ and a ‘486 Busy Here’.
The short answer is that all 6xx responses will terminate SIP dialog, and any pending searches. Alternatively, a 486 response would indicate that the user is not available at a particular request-URI.
I have constructed a video that demonstrates the difference between these two responses. It might even answer a few questions you didn’t even know you had.
Examining the 486 ‘Busy Here’ and 603 ‘Decline’ SIP response codes
SIP Downloads *.pcap
This video mentions two accompanying (*.pcap) files. These can be found here: (posting soon)
Russell, Awesome video! That was the best presentation of these concepts, I have seen anywhere! I’m just a little bummed that the *.pcap files aren’t available! Great Job!
Nice video, explaining the differences, but why would the phone send 603, Does it know that the user can not be contacted anywhere, does it have that knowledge? its just could have send 486, like in the first case. Not sure the video addressed the differences between 486 and 603.
Nice Video, perfect explanation! Hopefully there are more videos in future.
greetings Rene