If you travel a lot, or even just a little, you’ll be sick of roaming bills, or frustrated by the inconvenience of the cheaper alternative: buying a local SIM and switching it with your regular one. Hong Kong-based Tink Labs believes it has a better solution, a designated mobile device in your hotel room that you can use for free, and it has raised a whopping $125 million to expand its idea to cover more hotels worldwide.

The new financing was provided by existing investor and manufacturing giant Foxconn (via its FIH Mobile unit), with participation from Sinovation Ventures, the investment firm from ex-Google China head Kaifu Lee, and Cai Wensheng, a prolific angel investor who is Chairman of popular Chinese photo service Meitu.

Tink Labs CEO 24-year-old Terence Kwok declined to provide the company’s valuation, but hinted that it is above $500 million.

“We’re not a unicorn yet, but are more than halfway there,” he said.

That would make it the highest-valued tech startup in Hong Kong, and certainly one of the most notable in Asia, yet Kwok is happy to remain discreet and focused on business.

“We’ve kept a low profile even though there’s a consumer element to the product,” he said.

Tink Labs began as a device rental service that targeted travelers at airports, but Kwok said it pivoted when the team found that the business wasn’t as scalable as hoped.

“We quickly realized people just want to get the hell out of the airport,” he said.

It remained focused on travelers, but moved its touch point to hotels where it has found traction, raising over $170 million from investors to date, today’s announcement included, and working with major groups like Starwood, Accor, Shangri-la, and Melia.

Tink Labs’ flagship product is Handy, a smartphone for hotel guests that takes the pain out of mobile roaming. You can make calls and send messages like a normal phone, but it also includes details of services available at your hotel and nearby activities. It even hooks into the hotel’s telephone system so you can order room service before you get back to your room, call a colleague via their room number, or phone the helpdesk if you’re out and about but need help talking to a taxi driver in the local language.

It’s a neat two-way model: guests get a device and free services, while hotels get a powerful channel through which they can engage their guests.

All of this comes for free because hotels are sold on the idea that Handy can increase their engagement with guests, which translates to higher spending.

A hotelier’s dream is a guest who not only stays in their rooms regularly, but uses facilitates and services like the on-site spa, steakhouse or minibar. That’s the kind of guest who generates serious revenue.

Four-year-old Handy believes it can deliver on that mission.

It touts a two-year independent study which, it said, found that guests would spend an additional $21 per night on average when staying in a room that includes a Handy device.

Kwok told TechCrunch in an interview that typically 30 percent of guests who stay in a room with a Handy will engage with hotel information via the device. Compare that to your own experience — when was the last time you opened that gigantic book of hotel services?

The Tink Labs CEO reckons that less than 10 percent of guests go down the traditional route and open the book of services. That severely limits additional revenue than a hotel can make. Tink Labs charges hotels an undisclosed subscription fee — “it’s certainly nowhere near $21,” Kwok said — which can help them increase their revenue. That fee varies based on the requests of a hotel, though its important to note that hotels are forbidden from charging guests to use a Handy.

Tink Labs works with Foxconn to produce its devices, but it is changing things up with plans to introduce phones next year that it has designed itself. Right now its devices are fairly standard although they run on a “modified version of Android that is heavily, heavily customized,” Kwok said. He’s ready to take things further and from April next year, the company will give hotels bespoke devices under its own brand that can do things like control the TV set in a hotel room, and more.

Beyond developing specialist hardware, Kwok said he intends to triple the current team of 150 people and expand its reach of seven international offices to go after more hotel partners across the world.

Right now, the Handy service is in over 100 hotels with nearly one million people using Handy devices each month, the company said. It started off focused on Asia, and Kwok said Handy is present is half of the hotels in Singapore and Hong Kong, while its reach in London is at nearly 25 percent. The goal is now to expand that presence into other tourist and traveler spots and beyond.

Updated 09/28 5:15 PDT to correct Handy business numbers