BERLIN — From Manila to Madrid, international consumers now represent more than three-quarters of the 232 million people who regularly use Twitter.

The problem is, Twitter is still figuring out how to make money from those users abroad. The company received 26 percent of its total revenue from markets outside the United States in the third quarter, compared with around 17 percent at the end of last year, according to regulatory filings.

Turning that global popularity into international ad sales remains tricky for the company, which is based in San Francisco, as it nears an initial public offering of stock. Many overseas brands are more skeptical of the impact of social media advertising than their American counterparts, while Twitter faces stiff competition from local social media rivals like Line of Japan, which already has hundreds of millions of registered users across Asia.

Twitter also has yet to expand its foothold in many international markets. That includes the global debut of its self-service advertising system, begun in the United States in late 2011, which allows brands to buy ads without talking directly to a sales representative. The company plans to bring that system to a number of global markets, according to regulatory filings.