Beyond not trusting hardware that old for something business-critical, I'd keep the following in mind:
-It would be unsupported by Avaya in all ways.
-can't install as a virtual machine on vmware, as the required version of vmware would be too new to have hardware support for that server
-you *might* get away with installing Windows Server with Hyper-V role to allow a IPO_R12 virtual machine to work. It would most likely work, but no guarantees.