In the early years of mobile evolution, mobile devices are enabled only with voice services that allow the users to communicate with each other. But now a days, the mobile technology undergone various changes to a great extent so that the devices allows the users not only to communicate but also to attain a variety of services such as video calls, faster browsing services,2d and 3d games, Camera, Banking Services, GPS services, File sharing services, Tracking Services, M-Commerce and so many. The changes in mobile technology may be due to Operating System or Hardware or Network or Memory. This paper presents a survey on evolutions in mobile developments especially on mobile operating system Architectures, challenges and Issues in various mobile operating Systems.