First of all let me say: Thank you 9000! I tried implementing this different ways but ended up on the same place you did - pretty much same constraints: only wav files (for now) and trying to compete with the phone application to change the symbolic link before it opens the file. I don't mean to say that I have developed a complete solution for this problem but thought that some people on this thread may want to know that I just release an application (MyContacts) that allow for some ring tone by group.