Going out, you program inside your own PBX Business phone systems. So this is essentially how trunk lines work. Like I say, right now we’re just talking about normal wires coming in from the telephone line, but this is the exact same case whether you’re using T1 or voice over IP trunks. This is the basic concept of how it works.
So we’ve talked about the Public Switched Telephone Network, the PSTN, we’ve talked about the central offices. Now we’ve talked about the trunk lines that come all the way to your building. Now once these trunk lines get to your building, they’re going to hit something called the PBX. The PBX is, for all intents and purposes, the telephone server. This is what routes the telephone calls that you’re making on the system.
So if you’re trying to call your boss in the room over and you just dial an extension, 345, the PBX is what routes the call from you here over to your boss. So the call goes into the PBX and then it goes over to the boss, the extension.
Here you can read about Small Businesses Necessities: AVAYA Telephone Systems