"For Alzheimer's patients we have what we call an invisible geo-fence," says Mark. "So if a patient leaves home it alerts us that they've left and we can live track them."
Pendants also come with fall detection.
"If you fall, we know," says Mark.
"We're all about independent living. It allows older people to stay living in their homes for longer."
People on their own can push the button and get in touch with the monitoring team if they need any sort of help, right down to an urgent plumbing job if a pipe has broken, for example.
"We've got an escalation plan," says Tammi. "Depending on what their situation is, their data comes up when the call goes through. If it's an emergency we can call emergency services."
As a monitoring company GPSOS is not allowed to hold medical information and until the button is pushed they are unaware of the client's location.
"For family harm they have a silent call, so they push the button, the call comes through and we're listening in silently while we're contacting the police."
"There's a safe word they can use," says Mark.
Everything, including the charger, is designed for ease of use, taking into account disabilities or difficulties. If the device is dropped, fall detection is activated.
As well as the pendants, smart ceramic watches will soon be added to the product line.
"The reason we call it the Independence Alarm is because we've got older ladies who slowly stopped visiting each other, confined to their homes. Now they know they can go out," says Tammi.
"If you go overseas we can switch it to 'roaming'."
GPSOS came about out of necessity. Mark knew there had to be something better than the existing personal alarms, but, search as he might around the world, he couldn't find exactly what he wanted.
"I'll take the best bits of everything I can and build my own," he says. "We started building the technology three years ago."
Eighteen months ago they started training staff.
Those monitoring can warn clients if their pendant needs charging or even if they've accidentally switched it off.
"We've had no failures," says Mark. "No-one else can do what we do."
GPSOS has a website with lots more information – GPSOS.co.nz