[OpenSIPS-Users] Identify an in progress call

[Andrew Mason]

Hi All,
We recently encountered an issue in our datacenter where an upstream switch 
between the CPE and the OpenSIPS server was dropping packets. Obviously for 
VoIP this is not ideal but it did expose an issue in our configuration. 

If the packet dropped was a '183 Session Progress' or a 'Ringing' then the CPE 
would send the same Invite (exact same packet) to which our server issues a 
407 Proxy Auth Required. At which stage the CPE seems to hang up.

My question: How can I determine if a call is already in progress for a 
particular Invite ?

Apologies if my terminology is not correct, please let me know if anything 
does not make sense. I have inherited this system and am still very much 
learning about SIP and OpenSIPS.

Thanks in advance
Andrew