First off, I assume you are talking about the OUTGOING order of things.
The POOLS Hunt between each other, in the order they are assigned to ARS.
That is, if you set up ARS to choose first the 899 pool, and then the 898, and 897 and so on, then 899 would be chosen first, followed by 898 and 897 and so forth.
The individual LINES within the pool are chosen more or less at random.
So, if you want Line 1 chosen first, let it be the only thing in the 899 POOL, Line 2 next, set it as the only thing in the 898 POOL, and so on.
But that wouldn't necessarily be very efficient.
I usually like to have a few lines in each pool, with the LAST FEW THAT I WANT TO GET USED FOR OUTGOING CALLS, in the LAST POOL CHOSEN by ARS.