I have two ring groups, "ring_group-1", "ring_group-2", one extension "post-1", is in the destination on this two groups. How can I configure this ring groups, or this extension, so when the call come to "ring_group-1 > post-1" it will ring for example by ring1.wav, and when call comes to "ring_group-2 > post-1" it will ring by ring2.wav.