Comment 3 for bug 1589229

So while its easy to add a Custom message received option similar to ringtone there are a couple issues.
First we need to either enforce a restriction on the size of the audio file, provide a way to truncate it for the user, or limit the playback time for the sound. Otherwise an entire sonata could play on a message.
There is also a bug where we delete all custom sounds from the dir when a new one is selected, so we should either make two subdirs or be smarter if either is in use.