Maybe if you have the MCDN keycode on the Norstar. Never tried it with Octel. If not, maybe a VMI? I've never played with a VMI, but here's some info.
Voice Mail Interface
There is also a Norstar Voice Mail Interface device (part# NT8B89DA). At the time of writing the only information that could be found was:
"The Norstar Voice Mail Interface (VMI) allows the connection of a third party stand-alone auto attendant/ voice mail system to a Norstar system (DR2 or higher). This interface provides the basics of integration; forward to personal greeting, return to operator, and message notification. Each VMI supports 2 ports on the AA/VM device and uses 2 station ports on the Norstar. Up to 10 VMI units can be used on a Norstar to interface an AA/VM system."
The VMI is basically a two port analog terminal adapter that provides disconnect supervision and signalling via DTMF. It is no longer manufactured and thus can only be found on the secondary market.