A report says the social media company has been busy tailoring advertisement formats and expanding local sales efforts to appeal to an expanding South American and Asian user base. By tapping into these markets, Facebook acknowledges that emerging markets are an important growth engine for the company, in terms of both new users and additional income, as U.S. signups have slowed.

In India, for example, where more than 100 million people belong to the social network, Facebook launched a campaign with L’Oreal’s (OR) Garnier that played off a cultural standard of “missed calls,” where people will call each other and hang up before connecting to signal either that they are outside or to call them back — to avoid incurring charges.

The Garnier ad allows users to click through, sending a missed call. The clicker then gets an automated call-back from the brand with content such as music, sport scores or messages from celebrities, according to a report in The Wall Street Journal.

Facebook is hoping to expand custom ad options like these to deliver promotions that are “better suited to meet the needs of people and advertisers in high-growth countries,” Kelly MacLean, a product-marketing manager who leads the emerging-market ad team, told the Journal.

“We’re thinking through where there are nuances from a local standpoint we can capitalize on,” she said.

Facebook, by expanding into these emerging markets, promises to help marketers reach traditionally closed-off demographics. Many users in emerging markets don’t access the site through expensive Internet connects, but instead through less-expensive handsets with limited functionality.

The company will continue to expand in these high-growth regions, adding sales offices in Indonesia and Colombia so far this year.