Exemplo de call back.
Tem que baixar app e instalar.
Vou realizar um manual melhor para postagem!

;################## CALLBACK ##############################################
[retornocall]
;verifica numeros cadastrados
exten => s,1,Answer()
exten => s,n,Noop(BINA RECEBIDO ${CALLERID(num)})
exten => s,n,GotoIf($[“${CALLERID(num)}” = “03284011893”]?200)
exten => s,n,GotoIf($[“${CALLERID(num)}” = “3284011893”]?200)
exten => s,n,GotoIf($[“${CALLERID(num)}” = “03288541499”]?200)
exten => s,n,GotoIf($[“${CALLERID(num)}” = “1189611102”]?200)
exten => s,n,GotoIf($[“${CALLERID(num)}” = “01189611102”]?200)
;Dial(SIP/abratel/${EXTEN},35,tr)
;dando tom de linha para usuario que liga
;exten=> s,200,Wait(10)
;exten=> s,200,Disa(no-password,callback-dial)
;eten=> s,n,hangup()
;exten => s,200,Callback(Dgv/g2/0${CALLERID(num)},callback,s,1)
;exten => s,200,Wait(1)
;exten => s,200,Callback(Dgv/g2/03284011893,callback,s,1)
exten => s,201,Hangup()

[callback]
;exten => s,1,Dial(SIP/23,30,rt)
;exten => s,n,hangup()
;exten => s,1,Wait(3)
exten => s,1,Disa(no-password,callback-dial)
exten => s,n,Hangup()

[callback-dial]
;exten => _2X,1,NoCDR()
;exten => _2X,n,SIPAddHeader(Alert-Info: Bellcore-r2)
;exten => _2x,n,Macro(disca,SIP/${EXTEN},tw)
;exten => 4,1,Dial(SIP/digavoip/03237224004,40,tr)
;exten => _372XXXXX,1,Dial(SIP/digavoip2/${EXTEN},60,L(360000)tr)
exten => _XXXXXXXXXXX,1,Dial(SIP/digavoip2/${EXTEN},60,L(240000)tr) ;em milesegundos 1hra=3600000
;exten => _0XXXXXXXXXX,n,Hangup()