More than 300,000 people in Bangladesh, one of Asia’s poorest but fastest-growing economies, have rushed to sign up to learn English over their mobile phones, threatening to swamp the service even before its official launch on Friday.

“We were not expecting that kind of response; 25,000 people would have been a good response on the first day,” said Sara Chamberlain, the manager of the discount service. “Instead, we got hundreds of thousands of people.”