Our 4G LTE network will remain in use for the foreseeable future. AT&T’s path to 5G using low-band spectrum started with  4G LTE Advanced technologies, which includes carrier aggregation, 4x4 MIMO and 256 QAM – that we have optimized. With  4G LTE Advanced technologies, we densify our network and upgrade the majority of our equipment so that it can be easily upgraded to 5G via a software release. This foundation enables us to deliver fast speeds now and upgrade to 5G when it is ready.  Our first standards-based 5G deployments (including the mobile 5G+ we began offering in 2018 in parts of 21 cities) will be “non-standalone” 5G. This service will be delivered using the LTE network core and a combination of 5G and LTE radio technologies (including  4G LTE Advanced technologies), with 5G radios carrying download traffic and LTE radios carrying upload traffic plus signaling and management functions. Ultimately, “standalone” 5G will use 5G radio access with a new 5G network core and will be interoperable with today’s LTE network. Even when stand-alone 5G is deployed, the LTE network will remain in place to provide voice coverage, and data coverage where 5G is not available.