asterisk users - Mar 2014 - 302 Moved Temporarily and channel variable

When a call is transferred to another extension using a blind transfer,
asterisk keeps traces of who is transferring in the BLINDTRANSFER variable.
If instead the call is "forwarded" using most phone call forward
feature, a
302 Moved Temporarily is sent back to asterisk

    -- Called SIP/104-DEVEL
    -- Got SIP response 302 "Moved Temporarily" back from
83.211.***.***:5063
    -- Now forwarding SIP/103-DEVEL-00000000 to
'Local/0039*****@authenticated' (thanks to SIP/104-DEVEL-00000001)

Unfortunately I don't find in any of the variables available in the Local
channel used by asterisk to place the new call, the originating extension.

In the logs asterisk says "Thanks to SIP/104-DEVEL..." but in which
variable can I find this value?

Leandro
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