In short; remember that changes made on your dashboard are configured for you by Obitalk. That can only occur if you let Obitalk manage the field that would normally be affected. This is one reason a device has to be reset to factory default before it can be added to an account.
If you add a number to the trusted callers list, Obitalk adds that number to the inbound call routes for SP1, SP2 & Line (& SP3 , SP4 for Obi202) for every device in the account.
This only occurs if Obitalk is managing that particular field. If you have manually made changes and unchecked the Obitalk Settings next to the field, Obitalk will not make any changes to that field. There is a red exclamation mark next to the fields that are being managed manually. Any trusted callers you want to use that device's SPx will have to be added manually for any field that Obitalk is not managing, even if the number has been added to the trusted callers list.
If you have the same few particular devices you want your trusted callers list to use, you can let Obitalk manage those fields. For the devices you do not want them to use you can just go in and uncheck the Obitalk Settings box for that field. You do not have to make any changes to the field for this setting to take place. You must submit the change before leaving the page. This makes it easy unless your device list changes for each particular trusted caller.
See RonR's post about trusted callers.http://www.obitalk.com/forum/index.php?topic=3094.0
You can test this by going to a device that is managed manually and checking the Obitalk Settings box for a SP inbound call route. The call route will automatically be populated with the trusted callers in your list.