SoftBank Corp. is in talks with Deutsche Telekom AG over a possible deal for T-Mobile US Inc., as the Japanese company looks for alternatives to enter the U.S. wireless market if its $20.1 billion deal with Sprint Nextel Corp. falls apart, according to three sources familiar with the situation.

SoftBank and Deutsche Telekom were in talks last year about a deal for T-Mobile USA and have had periodic discussions since then, but those conversations have intensified in recent weeks after Dish Network Corp. made a $25.5 billion counterbid for Sprint, two of the sources said.

Deutsche Telekom owns 74 percent of T-Mobile US, and one possibility is for SoftBank to buy that stake if the Sprint deal doesn't happen, the sources said.

SoftBank and Sprint declined to comment. T-Mobile did not have immediate comment. Deutsche Telekom did not immediately respond to a request for comment.