[Asterisk-Users] How to do something random?

[Ronald Wiplinger]

I want to change the below lines:

exten => _011.,1,SetGroup(line1)                ; set current group to line
exten => _011.,2,CheckGroup(1)                    ; check line1 does not 
have more than 1
exten => _011.,3,Dial,SIP/${EXTEN}@line-a            ; use line-1
exten => _011.,103,1,SetGroup(line2)                ; set current group 
to line
exten => _011.,104,CheckGroup(1)                ; check line2 does not 
have more than 1
exten => _011.,105,Dial,IAX2/xxxxx at line-b/${EXTEN}        ; use line-2
exten => _011.,205,1,SetGroup(line3)                ; set current group 
to line
exten => _011.,206,CheckGroup(1)                ; check line3 does not 
have more than 1
exten => _011.,207,Dial,IAX2/xxxxx at line-b/${EXTEN}        ; use line-3

exten => _011.,307,Busy                    ; Play busy if all lines 
already used


so that the three lines will be choosen random, but still only one user 
per line.

Can you give me  a hint?
BTW, I have not tested the lines yet, ... if you spot an error, please 
point it out.


bye

Ronald