If you were getting ready to bet on Sprint Nextel (NYSE:S) making a counteroffer to whisk MetroPCS (NASDAQ:TMUS) from the clutches of T-Mobile USA and its parent company Deutsche Telekom, there could be another buyout brewing to make you put that gamble aside.

Japanese No. 3 wireless carrier Softbank, founded and led by that country's third-richest man, Masayoshi Son, has been trying to round up enough money to make a bid on Sprint, according to Reuters. Sprint is the No. 3 wireless carrier in the U.S.

Softbank was the first Japanese carrier to offer Apple's (NASDAQ:AAPL) iPhone, but lost that exclusivity last year when rival KDDI also bought the rights to the iPhone. Once a software distributor, Softbank has grown into a diversified telecom and Internet business with a market cap of over $40 billion. The carrier's recent deal to buy smaller rival eAccess for $2.3 billion would make Softbank Japan's second-largest mobile operator behind NTT DoCoMo (NYSE: DCM).

The Japanese newspaper Nikkei has reported that Softbank plans to offer $19 billion for two-thirds of Sprint's shares. However, Nikkei has not provided a source for that information. If true, that would surpass the $15.5 billion Softbank spent in taking over Vodafone's (NASDAQ:VOD) Japanese operations in 2006.

This would not be the first time a foreign telecom would be making a bid for at least some control of Sprint. In 2008, Sprint's board turned back a $5 billion bid from Korea's SK Telecom (NYSE:SKM), which wanted to return former Sprint chairman Tim Donahue to the company as CEO after the forced resignation of former CEO Gary Forsee.

If Softbank does make an offer for Sprint that is eventually accepted, one has to wonder what effect, if any, the recent warning from the House Intelligence Committee regarding the cyber-security dangers allegedly inherent in equipment from Chinese manufacturers Huawei and ZTE would have on any foreign takeover of a major U.S. carrier.

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