There are two primary types of door intercoms, wired and wireless. If you have a new building under construction, then a wired system would probably be best. There is no better time to install wiring than before the drywall goes up. If you install CAT-5 wiring you can use the majority of the video or audio intercoms on the market. With a wired intercom system you won’t have to worry about any interference from other wireless devices.

If you have a pre-existing building, installing wiring may be cost prohibitive. That’s where a wireless system will benefit you. The one you choose comes down to the distance and obstacles between the outdoor and indoor stations. Some units only transmit at a range of a few hundred feet, while commercial models can go up to a couple of miles.

The other choice you’ll have is with features. One wired unit uses your existing telephones to communicate with the door unit. If you have a remote door lock, you can even hit the * key on the telephone keypad to unlock the door.

You can also use a video intercom so you can see who is at the door. You can even get a unit that records what happens at the door. There are no wireless video intercoms so you’ll have to run wires to use video.

Go to the Doorbell Intercom section of www.IntercomsOnline.com to see available door intercom units.