is there a way to fix an iPhone if it says "iPhone is disabled connect to iTunes"?

I have an older iPhone that used to belong to my dad, and I want to fix it to use as a backup phone in case something happens to his phone and he can't get a new one, but there's one problem with that: the phone is disabled. When I turn it on, all it says is "iPhone is disabled connect to iTunes". So I went and plugged it into my computer to try and connect it to iTunes, but iTunes popped up a box saying that it can't detect the device. I was wondering if there is a way to fix this, since the phone's been like this for about 2 or 3 years now.