Really fast and dirty solution for answer "Who put handset first?" on Asterisk. Idea based on "g" option in Dial, that works in a case if callee hangs up and not, if caller.
exten => _X.,1,Dial(SIP/Trunk/${EXTEN},,g)
same => n,Set(HANGUP_CALLEE=True)
exten => h,1,GoToIf($["x${HANGUP_CALLEE}"="xTrue"]?hangup-callee)
same => n,Set(CDR(userfield)=HANGUP_CALLER)
same => n,GoTo(end)
same => n(hangup-callee),Set(CDR(userfield)=HANGUP_CALLEE)
same => n(end),NoOp
And in CDR in userfield we will get who hung up first, caller or callee.