Mobile phone operators beware: yuilop is coming to drink your milkshake.

Imagine a world where you weren't tied down to a phone contract, where you could make calls abroad as freely as you do at home, and where your phone number isn't stuck on your SIM card. That's the world that yuilop, which just launched in the UK, claims it can introduce.

"I want to provide really free communication to the user," says yuilop CEO Julian Doppelhammer. "Free in both aspects. Free meaning no costs but also free meaning independent from [mobile phone] operators, independent from providers. A real Internet service."

Launched in Germany in 2011, yuilop began as a free SMS service and then moved to being a VoIP app. But now, by linking into the public switched telephone network, yuilop is able to provide you with a telephone number—one that lives in the cloud instead of on your SIM card.

Free calling and message apps like WhatsApp and Viber already exist. But unlike other VoIP apps, yuilop lets you contact landlines and people who don't have the app.

"Finally, we can become free from mobile operators. We can be free of roaming charges and independent of country borders," says Doppelhammer. "We are making communication free again."

At present, when people travel abroad, they either face exorbitant roaming charges for using their phone in another country, or they take the option of buying a local SIM card. Neither of these options make it convenient for people to contact you on your normal number.

With yuilop, your phone number isn't tied to your SIM card. Toss it out, buy a local pre-paid data plan, and continue using your phone and your number as you would at home.

An in-network currency, called credits, restricts the number of texts and calls that you can make to non-yuilop users. Those credits can be bought, but they can also earned by using the service.

"When you receive calls, you earn credits, when you make calls, you spend credit," says Doppelhammer. It costs £3.99 ($6.21) to buy 300 credits—calls to landlines in the UK cost one credit per minute (around 1p [2 cents] per minute).

The company says that it has around five million users in over 200 countries, but its yuilop.me phone number service is only currently available in the UK, Germany, Spain, and the US.

There are drawbacks. Even if you're using yuilop regularly and earning credit, you'll still have to buy credit every now and again. For example, you earn 2.5 credits for receiving an SMS, but it costs three credits to send an SMS in the UK. But if enough people use the service, Doppelhammer says it will be possible to build a truly free peer-to-peer phone network. And then we can say goodbye to phone contracts forever.

Doppelhammer is already living it: "I now live purely on Internet access."

This story originally appeared on Wired UK.