Comcast and Charter Communications announced on Monday that they will join forces to offer cell phone and data services in the U.S. The two media companies plan to work together to create better experiences for their customers by using the same 4G LTE network, according to Comcast chairman Brian Roberts. Comcast is expected to offer its new Xfinity Mobile wireless service this month. Charter Communications said they will offer wireless services by 2018. “By working with the team at Comcast, we cannot only speed Charter’s entry into the marketplace, it will also enable us to provide more competition and drive costs down for consumers at a similar national scale as current wireless operators,” Thomas M. Rutledge, Charter’s chairman and chief executive