GEOFF GROSS, 32, of Center City, is president of Medical Guardian, which sells medical-alarm systems to seniors. He started the company in 2005 in his apartment at Locust Street near 15th. In April, the fast-growing firm, which has 50 employees, moved into 12,300 square feet of new office space at 18th and Market streets.

Q: How'd you come up with the idea for the business?

A: My father was in the home-security business, so I got to learn about that, and medical alarms seemed like the same model. My goal was to start as a dealer. Others would handle the back-office operations and we'd be marketing and sales. When I started, I advertised online, calls would come in, I'd sell the calls and we grew.

Q: What's behind the name Medical Guardian?

A: The name just sort of stood out because it means protection.

Q: How's the biz model work?

A: We don't manufacture the alarms or monitor emergency calls. They are outsourced to a third-party monitoring center. You press a button on the alarm you wear around your neck or wrist. That transmits to a base unit that dials out to our monitoring center. People there pick up and ask the client if there's an emergency and they need help. We send EMTs, fire, police or family, friends and neighbors.

Q: How much do services cost?

A: We charge clients $29.95 a month, and that includes everything. No activation fee, no contract, and we only require a minimum three-month commitment.

Q: How many clients?

A: It's in the tens of thousands.

Q: Who's the typical client?

A: I'd say 75 to 80 percent are women. Our average client is an 80-year-old woman who is a widow and wants to continue living in her home. We have some couples, 60-year-olds and young people with disabilities.

Q: What's been the biggest challenge growing the business?

A: Finding the right mix of people to work here who can take us to the next level. We're gearing up to be a full-service company, taking on all the customer service, billing, shipping and retention and collection. We plan to add 20 more employees by year's end.

Q: How big is this market?

A: There are 2 million active medical alarms now. As boomers age, the market will grow.

Q: What separates you from your competitors?

A: We think active seniors should have this if they're alone and had a heart attack, a fall or a dizzy spell. It's about protection. We also want to have a relationship with our customer, where we educate and talk to them.

Q: How big a business is this?

A: Last year, we had revenues of $5 million to $6 million. This year we'll do $10 million to $13 million.

Q: What's next?

A: Our goal is to reach a younger clientele. We have cellular and GPS capability with some of our products.