A lot of the Avaya PBX systems are hosted on Windows servers, so you will more-than-likely end up monitoring a Windows server - which is better than nothing, and you get process monitoring so you can at least make sure your Avaya processes are running and can get alarms when they die.
You should be able to get the Avaya management system to send traps to Spectrum though using event configuration. This isn't off-the-shelf and will require you to become familiar with how Spectrum receives traps and converts them into meaning information (certification / event config / eventAdmin models etc).