If a URL is included in a say, but that URL is inaccessible, the URL will be recited utilizing TTS. For example, this:

say("Please wait while we transfer your call. Press star to cancel the transfer.");
transfer(["+14075551212","sip:12345678912@221.122.54.86"], {
    playvalue: "http://example.com/ElevatorMusic.wav",
    terminator: "*",
    onTimeout: function(event) {
        say("Sorry, but nobody answered");
    }
});

Will read back "h t t p colon" and so on, since the URL is invalid.