Alright guys, I think I know what he's trying to say.
I've had this similar problem before.
I think this is what he's trying to say...
1)He set a custom alert,(a song), for his text message.
2)He gets a text, and bingo - it starts playing his selected ringtone.
3)So he picks up his phone, goes to the text message, and wouldn't you know? The ringtone won't stop playing even though he's clarified with the OS that he's acknowledged the message, (therefore expecting the ringtone to stop). Hell, he may even be creating a response to the message already, but the alert still won't stop....
4)So what does he do? He sets a shorter ringtone; shortens the length of the song, hoping it'd make a difference.
5)BUT, it doesn't. Why? I believe this is because that is one flaw in the dash's OS, (if you wanna call it that). Even though you may have acknowledged the new text message, it will stay play THE FULL LENGTH OF THE ALERT you have assigned it.
EX) Phone says, "I have a new text?!, play the designated alert! What? You already know you have a new text message? I don't care mufucka, I got a job to do, and that's play the full [length] alert I was told to play!"
If you notice, the pre-installed text message alerts, are relatively short.
So did the programmers just say, "f-it, we can't seem to make it so the alert stops playing once a message is read/acknowledged, so we'll just install short alerts", who knows.