ring phone 1, after 10 seconds if not answered ring phone 1 and 2, after another 20 seconds if no answer, ring 1,2,3 and 4

[extensions]
exten => 5000,1,Dial(Local/1001@extensions&Local/1002@extensions&Local/1003@extensions&Local/1004@extensions)

exten => 1001,1,Dial(SIP/phone1)
exten => 1001,n,Wait(999)

exten => 1002,1,Wait(10)
exten => 1002,n,Dial(SIP/phone2)
exten => 1002,n,Wait(999)

exten => 1003,1,Wait(30)
exten => 1003,n,Dial(SIP/phone3)
exten => 1003,n,Wait(999)

exten => 1004,1,Wait(30)
exten => 1004,n,Dial(SIP/phone4)
exten => 1004,n,Wait(999)