The LG Quantum or Optimus 7Q (also known as the C900) is a slider smartphone which runs Microsoft's Windows Phone operating system. The LG Quantum was launched November 8, 2010 on AT&T. The C900 ran the Windows Phone 7.0 operating system out-of-the-box and was later updated to Windows Phone 7.5. The C900 also supports the Windows Phone 7.8 update which launched which offers the new Windows Phone 8.0 style tiles and other improvements. It is possible to upgrade it using an alternate method.