Here's what you need to know about Europe's first mobile carrier ad blocking deal

Three, the European mobile carrier, confirmed on Friday it is partnering with ad blocking company Shine to allow its customers to block mobile advertising.

The move is a significant milestone in the evolution of ad blocking. Three has 30 million customers, all of which could soon opt to block advertising on their mobiles - publishers risk losing out on revenue should a significant number of people take up the ad blokcing add-on.

The two companies had been hoping to officially announce the partnership at Mobile World Congress in Barcelona next week, but journalists twigged once they received an invite from Three to a press conference, which said the company would "announce it is committing to give consumers more control over their devices."

Three is owned by billionaire Li Ka-shing's Hutchinson Whampoa. Ka-shing is also an investor in Shine.

Shine installs its technology in mobile carriers data centers in order for ads to be blocked at a network leve.

Here's what we know so far about the deal.

Ad blocking will be an opt-in. Unlike with Shine's first publicly announced customer, Caribbean operator Digicel, ad blocking won't be turned on by default. Instead it looks as though Three will roll out the service as an optional add-on.

By offering ad blocking as a choice, Shine says the EU's recently-adopted net neutrality laws (which are not yet in force) do not apply to the service. Customers will opt-in directly with Shine, so it'll just be like downloading any other ad blocker app from the App Store. However, one "European Parliament source" told Forbes Shine and Three's plans would be illegal under the new laws.

It will be free for customers. The idea is that less of customers' bandwidth will be used up on downloading ads, so they're putting less pressure on operators' networks. The ad blocking technology won't be applied when phones are connected to WiFi networks.

Shine isn't getting paid ... for now. Shine's chief marketing officer Roi Carthy told Business Insider "we are not generating revenue right now. We have a longer play in mind, and so what we are focused on is opting-in consumers that want us to help them protect themselves from ad tech."

Around 95% of ads will be blocked. The companies say the technology will block ads in browsers and smartphone apps too. Shine also eventually plans to block native ads.

There isn't yet a launch date. Three says it will roll out in Italy and the UK at some point later this year. Here's the full announcement.