On Orange in the UK, my Treo 600 always showed a small icon of a cassette tape when I had voicemail waiting. I just upgraded to a Treo 650 on O2 UK, and now I don't see any onscreen notification.

Is this a known issue? Is there a fix? I'm sure O2-UK is not so obscure a carrier that the Treo650 can't handle it, so I am at a loss.