Don't confuse COR Restriction Groups with COR Restriction Numbers
Each device on the system is assigned a COR Restriction Number
In ARS you assign your different routes to different COR Restriction Groups.
If a device's COR restriction number is found in a COR Restriction Group then that device will be denied calling for that route.
Simple Example (what I typically Use)
Device COR Numbers
1 - Restrict All except 911(default)
2 - No Restrictions
3 - National, Local and Tollfree
4 - Local and Toll Free
5 - Local Only
COR Group Assignments
1 - ALL COR Numbers
2 - All but COR number 2
3 - All but CORs 2,3
4 - All but CORs 2,3,4
5 - All but CORs 2,3,4,5
10 - No COR Numbers (used for 911)
Routes
Route1 - Restricted numbers - COR Group 1
Route2 - Country Code Dialing - COR Group 2
Route3 - National Dialing - COR Group 3
Route4 - Toll Free Dialing - COR Group 4
Route5 - Local Calling - COR Group 5
Route10 - 911 Dialing - COR Group 10
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What's most important is that you realise ... There is no spoon.