sentences:  The system also began providing real-time train information by phone in 2010.The New York City Subway began installing its public address/customer information screens, commonly known as "countdown clocks", in its stations in 2007.In 2012, the system began offering SubTime, a website and iPhone app for real-time train arrival estimates for several of its subway services, and the arrival data are shared with outside software developers to support creation of additional apps.