As the Los Angeles Times highlights, the two companies will offer separate wireless services to customers but will work jointly on behind-the-scenes issues like device-ordering systems and customer billing. This approach, they said, will allow them to better compete against national wireless operators.
Interestingly enough, Comcast and Charter have agreed not to acquire or merge with other wireless players without the other's consent for a period of one year.
It may seem odd for companies in the same industry to join forces and eliminate competition but as the Times notes, their cable service territories don't overlap and thus, they aren't really direct competitors.
Comcast officially announced its wireless phone service, Xfinity Mobile, in early April. It'll operate as an MVNO that piggybacks on Verizon's nationwide network when it launches in the coming weeks. Charter's service, meanwhile, isn't expected until sometime next year and doesn't yet have a name.
Some in the industry are speculating that Comcast and Charter could together make a move to acquire a major carrier like Sprint or T-Mobile. The latter company was nearly scooped up by AT&T in 2011 but regulatory hurdles ultimately derailed the deal and gave T-Mobile the cash it needed to help reinvent itself. The company has since overtaken Sprint as the third largest wireless provider in the US.