I always use virtuals, DIL a trunk to any virtual, let's say 250, assign that virtual to one of the keys on the phone, doesn't have to a physical button, example if the phone is 12 button you can assign the virtual to button 24. Program that button to ring, you can also assign different ring tones. You can setup 250 as subscriber (assign voicemail key 250 to one of the buttons on the user phones, it will flash with message) or you can assign 250 as a routing box.

I found this way to be less of a headache than ring groups.

We get old too soon, smart too late