[incoming]
include => afterhours|18:00-7:00|fri-mon|*|*
exten => 8888888888,1,Answer
exten => 8888888888,2,Goto(xmenu,s,1)

[afterhours]
exten => 8888888888,1,Answer
exten => 8888888888,2,Wait(2)
exten => 8888888888,3,Background(please-wait-connect-oncall-eng)
exten => 8888888888,4,Dial(IAX2/user@provider/18007774445,12)
exten => 8888888888,5,Dial(IAX2/user@provider/18007774444,12)
exten => 8888888888,6,Voicemail(u668)