Set a variable after picking up the phone?

Question

Asterisk

It is necessary to somehow save the time of raising the tube. The variable does not want to be established in any way.

[test]
exten => _XXXX,n,Dial(SIP/${EXTEN},10,m,U(sub-answ-call-start))
exten => h,1,Set(CALLS_HISTORY()=${answered -call-start})
[sub-answ-call-start]
exten => s,1,Set(answered-call-start=${STRFTIME(${EPOCH},,%Y-%m-%d %H :%M:%S)} )
exten => s,n,return

Answer 1

If so?

[test]
exten => _XXXX,n,Verbose(0,-----Call-Start-----)
 same => n,Set(CHANNEL(hangup_handler_push)=hdlr-call-end,s,1) 
 same => n,Dial(SIP/${EXTEN},10,U(sub-answ-call-start))
 same => n,HangUp()

[sub-answ-call-start]
exten => s,1,Set(__ANSWER_CALL_START=${STRFTIME(${EPOCH},,%Y-%m-%d %H:%M:%S)})
 same => n,return

 [hdlr-call-end]
exten => s,1,Verbose(0,-----hdlr-call-stats-----)
 same => n,Set(ANSWER_CALL_END=${STRFTIME(${EPOCH},,%Y-%m-%d %H:%M:%S)} )
 same => n,Set(CALL_TIME=${MATH(${ANSWER_CALL_END}-${ANSWER_CALL_START},int)})
 same => n,return