The document discusses how APIs provided by mobile operators in emerging markets are enabling startups to build new mobile services. It provides examples of operator API programs in places like the Philippines, Africa, and Pakistan. The most commonly used APIs by startups in these regions are SMS, USSD, billing, location, and mobile money APIs. Several case studies are presented of startups leveraging these APIs, such as a Philippine app using SMS and billing APIs to allow bus ticket booking via airtime, and a Senegalese marketplace accessing users via USSD and accepting payments through operator billing. The document advocates for operators in emerging markets to adopt startup-friendly API strategies to help foster innovation.