Dear Kieron;
Suggest you check SPA9000 Admin Guide, page 78, some examples:
Specifying a hunt order for FXO lines on one SPA400 unit. This is configured on the SPA9000 Call Routing Rule.
EXAMPLE: (<:L2{1,2}>8xx)
Line 2 is configured for a SPA400. This line is used for any dialed sequence that starts with 8. The preference is to seize port 1. If port 1 is unavailable, the next preference is to seize line 2. If neither port is available, then the call fails.
Specifying a hunt order for FXO lines on multiple SPA400 units
EXAMPLE: (<:L4{1},3,2{2,4}>9xx)
Lines 2, 3, and 4 are configured for SPA400 units. These lines are used for any dialed sequence that starts with 9. The preference is to use Line 4, port 1. If it is unavailable, then any port on Line 3 can be used. If Line 3 is unavailable, then the next choice is Line 2, port 2. If it is unavailable, the next choice is Line 2, port 4. If it is unavailable, then the call fails.
Hope this helps
Alberto