[Asterisk-Users] Please explain this streaming example to me

[Flash Love]

I believe that I found the example below while reading at the voip site. I 
understand the elements i.e. extensions, conference room assignment, etc. 
What I can not conceptualize is how do individuals using exten 1000 join the 
stream at exten 1002. 


; Icecast streaming
;
; Conference Room
exten => 1000,1,Answer
exten => 1000,2,Wait(1)
exten => 1000,3,MeetMe2(1000)
; Music On Hold
exten => 1001,1,Answer
exten => 1001,2,Wait(1)
exten => 1001,3,MusicOnHold(random)
; Stream
exten => 1002,1,Answer
exten => 1002,2,Wait(1)
exten => 1002,3,Ices(/etc/ices.xml)

Thanks
Flash