S500i question [Waiting message reminder]

Hi guys,

I have an S500i, and I really enjoy it. Debranded it last week and have been loving it. However, something's bugging me - it doesn't seem that there is any way to set the phone to repeatedly chime or vibrate on a timer when there's a waiting message.

Am I missing something, or is this feature nonexistent?

If it really doesn't exist as a feature on this phone, is there any way to customize the firmware such that I can add in that sort of reminder? Or does such a customization already exist?

Much obliged for any help or suggestions.