Facebook has found a better connection for advertisers and mobile users, particularly in emerging markets and out-of-range locations.

Advertisers can now target their Facebook ads based on how strong someone's phone signal is when they visit the social network. That means advertisers can limit data-heavy ads like video to people on strong 4G connections and run light-bandwidth text ads for those on 2G connections.

Facebook's new cell-signal targeting works across all of the company's ad units, including auto-play video ads where those are available, and in conjunction with all other targeting options. Advertisers can also use the option to target ads across Facebook's mobile network of third-party apps, a spokeswoman said.

The news could benefit U.S. advertisers looking to run mobile video ads but unsure whether people will have a hard time watching on the go. The bigger upside for advertisers, however, may be in marketing to audiences in developing countries like India and Thailand that generally have weaker cell reception and more phones that can't accommodate high-bandwidth content.

That could help Facebook close the yawning gap between its users' locations and where it makes its money. The U.S., Canada and Europe accounted for 72% of the $2.7 billion Facebook generated in second-quarter ad revenue, but only 38% of the 1.3 billion people who checked in on Facebook each month. Adding urgency to the matter, Facebook's user base in the remaining developing markets is growing four times as fast as its combined user base in the U.S., Canada and Europe.

In the U.S., Facebook can roll out expensive ad products like auto-play video ads without too much worry over whether those videos will lag on an iPhone. But 66% of the 100 million people in India who check Facebook each month are using less powerful so-called feature phones.

The new targeting capability joins a big Facebook push to make sure its business can grow in developing marketers along with its audiences there. To make sure it's not leaving money on the table in countries dominated by feature phones like India and South Africa, last year Facebook added the ability to target ads specifically to the lower-end devices. And last month the company made it easier for people in India to receive content and advertising on their phones without ringing up big bills.