Felipe Neuwald wrote:
  

ISP1:
NAS 1: 10.1.1.1
NAS 2: 10.1.1.2
NAS 3: 10.1.1.3

ISP2:
NAS 1: 10.2.2.1
NAS 2: 10.2.2.2
NAS 3: 10.2.2.3
    

Try this:

huntgroups file:
####
ISP1    Client-IP-Address == 10.1.1.1
                SQL-Group == ISP1
ISP1    Client-IP-Address == 10.1.1.2
                SQL-Group == ISP1
ISP1    Client-IP-Address == 10.1.1.3
                SQL-Group == ISP1

ISP2    Client-IP-Address == 10.2.2.1
                SQL-Group == ISP1
ISP2    Client-IP-Address == 10.2.2.2
                SQL-Group == ISP1
ISP2    Client-IP-Address == 10.2.2.3
                SQL-Group == ISP1
####

Now instead of the radcheck table, use the usergroup table like this:

+-------+--------------------+-----------+
| id    | UserName           | GroupName |
+-------+--------------------+-----------+
| 1     | user@example.com   | ISP1      |
| 2     | user2@example.com  | ISP2      |
+-------+--------------------+-----------+

It should just work.