[Freeswitch-users] How to get information of callee when the call is forwarded

hi, Folks I have come to a question when dealing with call forwarding: A and B are using Mobile Phones with PSTN. C is another Phone Number but connected with FreeSWTICH Instance which pickups any calls C receives. A calls B, B forwards to C, then FreeSWITCH routes A to an extension, in this extension, I would like to extract the Information of B, like its phone number, etc. I have checked the variables in the channel, but it doesn't contain information of B. Can any one help? Thanks. BTW, one related topic: http://lists.freeswitch.org/pipermail/freeswitch-users/2013-May/096044.html