What is the car telling me?

[billh]

I've had the car 15 years now. A couple of days ago it started making a single high pitched beep as I turn off the ignition, never heard it before. There's no visual warnings on the IPK and car behaves perfectly normal. Any ideas what it is telling me? There has always been a lower pitched sound a few seconds after switch on, but that is to tell me there's no phone connected and there's a brief message "NO PHONE" on the radio screen.