I have faced strange behavior of Cisco/Linksys PSTN gateway - SPA400.
SPA400 answers "400 Bad Request" to some INVITE requests.
I know that "400 Bad Request" usually means wrong sip syntax but I can't find what is wrong exactly.
I've attached samples if sip requests (INVITE and answer on it) and logs of SPA400 for successful (Good) and failed (BAD) call.
192.168.192.81 - IP of SPA-400
78127405999 - destination number
192.168.192.95 - proxy server
Could you please help my to find what is wrong in these calls.