[Freeswitch-users] Using reason header from SIP 183 message inside dialplan

Hello, I have a Vodafone SIP trunk connected to my freeswitch box. Everything works fine excepting one thing: I am unable to differentiate when a dialed number is busy or unavailable (line disconnected, mobile phone out of coverage area, &c). My provider signals this kind of situations inside a SIP 183 Session Progress message with reason header (user busy, subscriber absent, ...). How can I use/get that reason header inside dialplan? Sofia log uploaded here: http://pastebin.freeswitch.org/22101 Regards, Lucian