We have an old MICS that says software ver #: SP: 30ARF01 NAT, which I think is MICS ver 2.0

I would like to know if we can install a new CallPilot 150 for this PBX?

No, you need to upgrade the software to at least 4.1.

Contact your local vendor.

Thanks for the reply. We don't have a Vendor to support, is there is a way I can upgrade it by downloading the software?

No. There's always a Nortel tech in your area. Let your fingers do some walking.