[Freeswitch-users] Access to Cause filed in Reason header

Hello list some of our providers include a Reason header in negative replies to an INVITE. For instance, they might include a cause=65 inside a Sip 503 reply. We need to react upon some of those ISDN causes: in this particular case with if Reason header were absent we would simply do nothing but let FS to send the response upstream; but if cause=65 in present we want to resend the call to the same provider with a different set of offered codecs. Is there any way to access to the content of that header?. Our applicatiion listens to the event socket in inbound mode but I haven't found a way to do this. Any help would be appreciated. Regards Javi