Strange event in the music of ringing groups

I have a night CONDITION FROM that does get calls on a group to Guale is associated with a music …

Now it will seem strange, but when the call comes from the same telephone operator works if the call comes from another telephone operator you only hear the ringing …

Someone has already happened such a thing , or someone has an idea …

Other details : If you listen to the call recording is always correct , in addition if you use a group instead of a queue always works well …