Northern Telecom Meridian M5316 business telephone

I've learned a lot of cool things at my new job, both related to the work I'm doing, and incidental things which I research myself. One example of the latter is the working of business telephone systems, which I've never been up close and personal with until now. In particular, I've taken quite an interest in Northern Telecom, both in their history as a company, and in the residential and business telephones they made. This video concerns the Nortel product I've taken the most interest in, the Meridian series of digital business telephones. In this video, which takes place in a conference room at work, I give a brief history of Nortel, and we explore, and demonstrate in a call, a Meridian M5316 centrex telephone. The methodology by which most business phones work is called a Private Branch Extension, or PBX. A PBX may have one or more standard telephone lines coming in, and distributes calls to one of multiple phones in the building. In the case of most phones, the phones communicate