Comcast and Charter have reportedly started negotiating with Sprint, as the two biggest cable companies in the US explore the possibility of buying the wireless carrier or investing in its network.

Comcast and Charter last month announced an agreement to cooperate in their plans to sell mobile phone service, an agreement that also forbids each company from making wireless acquisitions and investments without the other's consent for one year. Yesterday, The Wall Street Journal reported that "Sprint has entered into exclusive talks with Charter Communications Inc. and Comcast Corp. as the cable companies explore a deal that could bolster their plans to offer wireless service, according to people familiar with the matter."

There are a couple different arrangements being considered. In one, the cable companies would invest in "improving Sprint’s network in exchange for favorable terms to offer wireless service using the carrier’s network," possibly by taking an equity stake.

Comcast and Charter already have agreements with Verizon Wireless to resell that company's mobile service under their own brands, and Verizon's network consistently outperforms Sprint's. But a deal with Sprint "could provide much better terms" than the companies' deals with Verizon, the Journal wrote.

Key Charter investor pushes for merger

The less likely scenario is for Comcast and Charter to jointly buy Sprint. Chairman John Malone of Liberty Media, Charter's largest shareholder, is apparently interested in such an acquisition.

Malone "has been trying to convince Comcast Chief Executive Brian Roberts for the past year that the companies should jointly buy a carrier like Sprint, according to people familiar with the matter," the Journal reported. But Roberts is reportedly skeptical.

"So far, Mr. Roberts has been reluctant," the Journal wrote. "His goal is to secure a better reseller agreement as Comcast jumps into the wireless business, according to a person familiar with his thinking."

Comcast and Charter both already have wireless resale agreements with Sprint stemming from a deal made in 2008, though the companies are not reselling Sprint service today, a source familiar with the situation told Ars. Comcast's primary interest in the current negotiations is improving the terms of that reseller deal, the source said.

Sprint, Comcast, and Charter agreed to make their talks exclusive until late July, meaning that Sprint/T-Mobile USA merger discussions are "on hold" for now, the Journal report said. But Sprint agreeing to a new reseller deal with the cable companies "wouldn’t preclude a subsequent merger between Sprint and T-Mobile," the report said.

Sprint, Comcast, and Charter all declined comment on the Wall Street Journal report when contacted by Ars today.

Comcast's new mobile service that resells Verizon data, available only to Comcast home Internet subscribers, recently went on sale. Charter has said it intends to offer similar service in 2018.

Disclosure: The Advance/Newhouse Partnership, which owns about 13 percent of Charter, is part of Advance Publications. Advance Publications owns Condé Nast, which owns Ars Technica.