$7 and $10/mo UMB for dumbphones (3G and CDMA) and HTC Touch (CDMA)
$15/mo UMB for Palm Pre (CDMA)
$30/mo UMB for windows PDA (CDMA)
$30/mo UMB for BB (CDMA BIS)
It depends which Bell UMB the CSR thought you were talking about.
The $30/mo plans are upgradeable to 3G phones for sure.
edit - BTW, the UMB plans aren't offerred anymore, but some employee purchase plans still have the UMB option embedded. You could still get UMB added today if it's still offered as part of an old employeee purchase plan that is still in effect