4G, short for the fourth generation, is the fourth generation of mobile telecommunications technology succeeding 3G. A 4G system, in addition to the usual voice and other services of the 3G system, provides mobile ultra-broadband Internet access, for example to laptops with USB wireless modems, to smartphones, and to other mobile devices. Even though it is a successor technology of 3G, there can be significant issues on the 3G network to upgrade to 4G as many of them were not built on forwarding compatibility.