Inter-Tel telephone controller?

I was given a large set of industrial/professional office telephones. One of them is an Inter-Tel INT 1400 with an EXP9300 handset. This is really the only one I have an interest in using because I want a cordless telephone with a longer range than the average household phone. In order to use this telephone at my house on my regular phone line, I know it needs some sort of a controller/modem/router thing that it plugs into, it won't work when plugged directly into my phone line. What is/are the model(s) of this device that are compatible with my telephone? Where can I purchase them used/refurbirshed, I don't want to spend a lot of money? If I were to have the proper controller box, would it work off of my regular landline phone line or would it need a different kind of connection?