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How to Choose and Install an Intercom System

Let’s address the most common questions we get from home and business owners about adding a surveillance security system.

If you have additional questions, contact us to discuss security system options for your home or building. We’re here to help!

How our Telephone Integrated Systems Work

Q1: My parents are older and have difficulty getting up and around. They frequently miss visitors because they can’t get to the door quickly. I’m also concerned for their security.

What intercom system should we install that will protect their safety while allowing them to give access to family members, friends and caregivers?

A: Our most popular solution for this scenario is to install one of our Telephone Integrated Intercom Systems. ILUS Electronics carries these systems:


The first three systems include a Telephone to Doorphone Adapter that works with a landline, either corded or cordless. The second component is the Doorphone installed at the door or gate.

The Telephone Entry PBX Call Forwarder with Anti-Vandal Door Phone is our newest and most advanced system. It can be used with a cellphone or a landline.  See below for more details.

The landline systems are simple to use. When a visitor arrives, they use the door phone to call the occupants.

This call sends a distinctive ring to their phone, so they know it’s a visitor at the door or gate. If the homeowner chooses to allow the person in, they press “0” and the door is unlocked.

The system has a call-waiting component too. If a visitor arrives while the homeowner is on the phone, the caller is put on hold by pressing the # key. The homeowner can then speak with the visitor at the door and allow access, if desired. Complete instructions that are easy to follow are included with every system.

Additional features include listening to what’s going on outside their door by picking up the phone and pressing #1 for the first Doorphone and #2 for the second Doorphone in two-phone systems. Again, we include complete, simple instructions with each system.

ILUS Electronics offers intercom systems for one-door/gate and two-door/gate installation. Click the links below for more information on these systems:

Telephone Entry Systems One Door

Telephone Entry System Two Door

Telephone Entry PBX Call Forwarder with Anti-Vandal Door Phone

You’ll enjoy expanded features with this leading-edge system. It offers the same features as those systems described above.

In addition, calls made from the door phone can be sent to any phone, anywhere, including a cellphone. The enhanced functionality lets you know who’s at your door when you’re home or away. It enhances security, because you can always give the appearance of being at home, even if you don’t open the door.

Two systems are available, a voice-only system or a voice and video system that also includes call-forwarding that allows visitors to leave a message.

These links provide more information:

Telephone Entry - PBX - Call Forwarder with Anti Vandal Door Phone

 Video Intercom 7" monitor with anti-vandal PBX doorphone and call forwarder

Wired and Wireless Video Intercom Systems

Q2: I’d like to learn more about systems that use video, so I can see the person at the door or gate. What’s available?

A:  Video Intercom Systems allow you to see who is at your door or gate and speak with to determine who they are. Lighting allows you to do this at night. If you choose to allow the person access, you can use the system to unlock the door.

Wireless systems are easy to install, but they have drawbacks. Their range is limited to as little as 50 feet and outside interference may make communication difficult or impossible. Communication that is not electronically encrypted may be captured by a third party.

Wired systems are more dependable and less susceptible to interference, so the sound quality is outstanding. The communication is secure too.

Installing Distances for Wired Video Intercom

Q3: What is the maximum distance capacity for wired video intercoms?

A: Here are the maximum wiring length between the video door phone (a.k.a. outdoor station) and the most distant monitor in the installation chain:

  • Traditional 4-Wire Video: The maximum distance is approximately 100 feet with standard AWG22, 4-conductor shielded, untwisted wire. When using 75 Ohm coaxial cable for video line, the distance increases to 250 feet.


  • 2-Wire Video Intercom: Depending on the installation conditions, the maximum wiring length can be 700 to 800 feet. In these applications, the cable used is AWG14, 2-conductor unshielded, twisted cable with each conductor stranded.

Getting the Most from your Intercom System

Q4: How many Monitors and Doorphones should be installed in the system?

A: Here’s your capacity with both 4-wire and 2-wire systems:

  • 4-Wire Video Intercoms: Typically, up to two Doorphones and three monitors can be installed. When the distances are short, a fourth monitor is a possibility.


  • 2-Wire Video Intercoms: Typically, up to four Doorphones and 16 monitors can be installed in a single-family home and up to 32 monitors in and apartment or commercial building. These are estimates; the final determination will be made on the job site when measurements for wiring length and the determination of wiring types are made.


If you have additional questions, we have the answers. Call us today for the information you want, and we’ll be happy to help.