This is driving me nuts.

I have an iPhone 3G, Unlocked and Jailbroken with ultrasn0w 1.0-1. Inexplicably, I stopped receiving voice mail notifications about three weeks ago. It had been working fine up until then. I do not get the voice mail SMS, nor does the red badge appear on the voicemail icon.

I'm on Rogers (Canada) with a normal data plan.

I've isolated the problem to the iPhone - voice mail notifications work correctly when the SIM card is in other phones.

I've tried "Reset Network Settings" multiple times but the problem has persisted. Any ideas what's going wrong?