Sprint Corp.¡¯s resumed talks about a potential merger with T-Mobile US Inc., being held at the same time as discussions with cable companies, shows the lengths billionaire Masayoshi Son is taking to build scale for a wireless carrier facing increasing competition in the U.S.

The two mobile operators restarted discussions after Sprint¡¯s exclusive negotiating period with Comcast Corp. and Charter Communications Inc. expired at the end of July, according to sources.

Son, who leads Sprint¡¯s largest shareholder, SoftBank Group Corp., is pursuing all options for industry consolidation as he continues to weigh a potential offer for Charter. SoftBank has been considering making a formal takeover bid for the cable company and combining it with Sprint, people familiar with the matter said earlier.