As Facebook initiative Internet.org approaches the second anniversary of its introduction and the first anniversary of the launch of its flagship app, the project is inviting mobile operators to become delivery partners. An update posted by Internet.org says that the project is succeeding in its goal of bringing people in underserved markets online, first as users of free services, and then as paying customers.

Since it launched in Zambia in July 2014, the Internet.org app has become available in 17 countries through “more than a dozen” mobile operators. The organization says the introduction of its free zero-rated data app speeds up internet adoption by 50 percent, and that over half of those using the service begin paying for data within 30 days.

The organization has struggled against the perception that it inherently privileges some service providers over others, in direct opposition to open Internet principles. These net neutrality concerns led India’s Save the Internet coalition to accuse the project of trying “to confuse hundreds of millions of emerging market users into thinking that Facebook and the Internet are one and the same.”

Facebook responded by launching a developer platform to bring in more third-party apps in May.

To expand its own reach, while channeling those new paying customers to mobile operators, Internet.org has launched a partner portal with a form to submit for more information.

The International Telecommunication Union says over 4 billion people are yet to adopt the Internet, due largely to access limited by price and infrastructure coverage. The sheer size of that offline potential gives Internet.org a compelling case for mobile operators in emerging markets, and motivation to ignore the critics.