Reading AMM's documentation, it looks like Octel integration is suppported. I am not sure about other options such as PIMG, VPIM etc..You could network Unity with AMM using Cisco Unity Bridge (which is a separate product).
Note that you dont need to network voicemail systems together, unless you want to send messages from one system to another. Not sure if that is exactly what you are looking for.
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus