Dish Network Corp., Charlie Ergen’s satellite-TV company, made an unsolicited $25.5 billion offer for Sprint Nextel Corp. to challenge a bid by Japan’s Softbank Corp. for the third-largest U.S. wireless carrier.

Sprint investors would get $7 a share, consisting of $4.76 in cash and stock representing about 32 percent of the combined company, Englewood, Colorado-based Dish said today. That means the offer is $17.3 billion cash and $8.2 billion stock, and 13 percent more than Sprint’s April 12 closing price. Sprint rose as high as $7.24 in early U.S. trading.

Dish, a satellite-TV provider with no mobile-phone customers of its own, is seeking an entry into the wireless business and already owns relevant spectrum. Ergen is trying to top Softbank, Japan’s third-biggest mobile-phone operator, which in October agreed to pay Sprint $20 billion for a 70 percent stake as it seeks growth overseas.

Dish “ran up against the clock because you’ve got an offer from Softbank,” said Vijay Jayant, an analyst at International Strategy & Investment Group. “It’s the opportunity that given the current capital market environment you can get cheap capital for a good story.”

Consolidation Frenzy

Shares of Overland Park, Kansas-based Sprint exceeding Dish’s offer in early trading signals that investors project higher bids are yet to come. The shares closed at $6.22 in New York on April 12. Dish shares rose 2.7 percent to $37.63 on April 12.

Bill White, a spokesman for Sprint, declined to comment on Dish’s proposal. Takeaki Nukii, a spokesman for Softbank, wasn’t immediately available for comment.

Dish’s move is the latest twist in a frenzy of consolidation for the U.S. wireless industry. Smaller carriers are seeking out merger partners to help wage a stronger attack against the two dominant competitors, Verizon Communications Inc. and AT&T Inc.

Ergen, Dish’s chairman, also informally approached Deutsche Telekom AG about a possible merger with the German company’s T- Mobile division, people close to the situation said last week. Deutsche Telekom last week improved the terms of a proposal to combine T-Mobile with MetroPCS Communications Inc., a transaction that would unify the fourth- and fifth-largest U.S. wireless carriers.

Cash Pile

Dish and Sprint both held talks with MetroPCS before that company agreed to its merger with Deutsche Telekom’s T-Mobile in October, people with knowledge of the discussions said last year.

For Ergen, the billionaire founder of Dish, the goal is to break into the wireless business — part of a plan to decrease its reliance on the slowing satellite-TV market. Dish has accumulated a record $10 billion in cash, partly by selling bonds over the past year, giving it a war chest to expand into the new industry. Ergen’s $17 billion company now has the most money among U.S. television and phone providers, according to data compiled by Bloomberg.

Barclays Plc is acting as financial adviser to Dish.