Swedish mobile phone company Doro has unveiled a hard-wearing handset designed for people such as social workers, carers and builders who work alone.
The Doro 8020X features a red "call for help" button on the side.
If the button is pressed, the phone can send a text message containing its GPS location to up to five contacts.
There are other apps on the market offering a similar service for other mobile phones.
They can take over an existing "home" button for this purpose.
Chris Millington, managing director of Doro in the UK and Ireland, said he believed the company's offering was competitively priced and was easier to distribute on a bespoke device.
The Android-powered handset, which retails at £220 in the UK, is based around the concept of "tough phones", which are chunkier devices designed to survive rougher environments.
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It is also compatible with Doro's automated care centre, i-care, for which the company charges a 48-euro (£40, $52) subscription per year.
I-care enables employers to closely monitor the status of the phone, including battery power and periods of inactivity.
It can also send messages asking if the owner of the phone is all right.
It is designed for people who work on their own - either in hazardous environments or entering others' homes by themselves.
"We don't want to do 'me-too hardware', but to deliver our service on to someone else's [device] is not so easy," said Mr Millington.
"You need a system that's going to take over control of the device."
Until now, Doro had specialised in handsets for older people and it had 130,000 subscribers for its range of "digital telecare solutions", Mr Millington said.
Smartphone expert Ben Wood, from CCS Insight, said Doro was entering a competitive market, already crowded with both rugged devices, such as those offered by construction brands De Walt and Cat, and dedicated care apps.
"It is interesting Doro is making the jump from seniors to lone works, but I can see the synergies - many of the requirements are the same," he said.
"It has a strong position in the 'phones for seniors' market and works with all the main networks in the UK."