I'm not sure why someone advertising Inter-Tel would come tell you it's too old to work on, maybe he was just trying to sell you a new switch or hasn't been around too long. I think I have a 2.X Axxess still living.... it's a far cry from the new stuff but works fine for the customer. The biggest issue I see is figuring out what level you are at. The older stuff didn't tell you what level it was at without logging in and either connecting or giving an error telling you you were at the wrong level. I would look for anything on some paperwork or a sticker someone may have put on the CPU or cabinet.... Back in those days I usually wrote on the CPU with a sharpe the version

If you are unsuccessful getting someone to help you get your box back on line. You can look at the new Mitel 5000 HX controller it will allow you to keep the handsets you have if they are in good shape it will save you a few dollars.

If you get some info send a PM or call and I'll try to help get you back on line
Randy