Apple is exploring the idea of having two SIM card slots in its iPhones. The Cupertino-based company has registered a patent for a dual-SIM card technology that involves two separate antennas. Though not as popular in the US, and UK markets, smartphones with dual-SIM card capability are extremely popular in developing regions such as China and India. For instance, according to Counterpoint Research marketing firm, more than 90 percent smartphones sold in India, world's fastest growing smartphone market had dual-SIM card slot in them. But why does Apple care about India and China, you ask. The iPhones sales growth has dropped everywhere in the world, except India, which is also the world's second most populous nation, and world's second largest smartphone market. As per Apple's previous earnings call, sales of iPhones grew by 50 percent in India, and Tim Cook has said that he sees a huge potential in the country.