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Distributing VoIP Throughout Your Home, Part 2
Thursday, April 17, 2008
In our last piece, you found your Network Interface Device (NID) or demarc. Now I'm going to explain what you can do with your NID.
The NID boxes attached to most recently-built homes make it possible to completely disconnect all your home wiring from the telephone network by simply unplugging a single phone cord. This is useful for two reasons. First, if you are having problems with your telephone line (e.g. noise), you can easily determine whether or not the problem is inside your home wiring--typically your responsibility--or the problem is outside your home, which is the phone company's responsibility. You can plug in your own telephone at the demarc point and quickly make this determination.
Note that older NIDs or demarcs also provide this capability, but not with a standard RJ-11 jack. You'd either have to use a butt set, or destroy a RJ-11 cord, strip the wires, and hook up the wires directly to the terminals. I'd read more about telephone wiring on the Michigan Telephone site that goes into this in a lot more detail.
The other, more relevant reason you would want to disconnect your house from the PSTN network is that you have cut the cord with your PSTN provider and you want all the phones in your house to use a Voice over IP service. Even on lines where the PSTN provider is not providing dial tone, voltage is being sent down the wire. That voltage is enough to light up some phones, but it's also enough to fry analog telephone adapters from a service provider. This makes it critical for you to disconnect your home from the PSTN before you plug an analog terminal adapter into it.
Once you've done that, can you plug your analog telephone adapter in and expect it to go to all the phones in your house? Not quite yet. In the next piece, we'll go over the different ways your phone lines might be connected in your home.
