Welcome Home To Peace of Mind

Protecting what you love is our 1st priority.


Knock, Knock. See Who's There.

Now, you can answer your door from anywhere.


Smarter Mobile Control

Control your home or business like never before.


We Know Business Security

For over 50 years, businesses
have trusted us to get the job done.


Denver Security Systems
for Home & Business

We are United Security Systems & we've brought peace of mind
to thousands of Coloradans for over 50 years.

We are Colorado’s premier home security & business security company

Home Security Systems & Smart Home Control

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Business Security Systems & Fire Alarm

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Property Crimes Per Day In Colorado
Average Loss Per Burglary
Number of Years We've Been in Business

Get your FREE security quote today!

Let's Get Started!

We’re now Mountain Alarm Fire & Security.

Across Denver & the Front Range, there’s no one better than us.


Mountain Alarm Fire & Security’s focus for over 60 years has been home & business security & fire services for tens of thousands of customers across 6 Rocky Mountain States. We’ve done this a long time & we’re the experts.

Our Team

Our team members have an average of 11 years in the security business.  Our  training programs keeps us ahead of the curve in the areas of home and business alarm system & security cameras.

Best Security Technology

We only use the best security equipment. We recommend and sell the best security systems for your needs. Our alarm systems are reliable, cutting edge & simple to use.


We take the time to consider your Colorado business and home security needs.  We design your monitored security system with your needs in mind. It all starts with a free security evaluation with our team.

We’re Local

Since 1957, we’ve made Denver, Colorado our home as United Security Systems, and now as Mountain Alarm Fire & Security, we’re still local and the same team helping our customers here.

Personal Service

As home security systems and business security experts, you can always count on us to deliver the personal attention and care you deserve.

Security System Monitoring

Your security system is only as good as the monitoring. We use the nation’s best UL-listed Central Station so you get local customer service plus quick response time and reliability so your alarm is monitored 24/7.


We don’t just sell you a security system and walk away like those other guys. We also service all types of home security systems & provide a warranty on our work.


Don’t take our word for it.

See what our clients are saying about us:

Thank you for 17 years of professional service. The personnel at United Security Systems have always been courteous & helpful.

Margate M

Thanks to United Security Systems, I may be able to start watching scary movies again knowing the bogey man won't be sneaking through my window later that night!

Emily T

Customer service at its best! I couldn't have been more pleased with the support provided to us.

Debbie G

I wanted to thank you and your team for the installation at our new facility. Everything is going just great, thank you all for doing such a professional and seamless job of getting us moved.

Bill Y

You have been extremely helpful and responsive throughout this process of getting our alarm installed. We really appreciate your quick response and talking through the options with us.

Jen J

After living in our home for 27 years, this move has been exhausting and, at times, mind-boggling but you made the security systems aspect that much easier!

Mary F