Assuming this isn't the actual CNAM value being delivered by the provider (hint: check this), it's most likely that the call is getting routed through Unity. For example, is the call hitting a call handler and the caller being transfered to your destination. Another possibility is that someone is routing all calls thorugh Unity so the Call Transfer/Screening rules can be applied to calls.
Easist way to check this is to place an incoming call and watch the Unity ports using the Remote Port Status Monitor tool.
If the call is legitamtely going through Unity and you want to see the original CNAM instead, the CallManager Service Parameter "Display Original Calling Number on Transfer from Cisco Unity" is likely what you want.
