April 7 (Bloomberg) -- Blackstone Group LP, KKR & Co. and Carlyle Group submitted bids for the mobile-phone operations Verizon Wireless is selling following its acquisition of Alltel Corp., according to people familiar with the situation.

Buyout firms KKR and Carlyle made a joint bid, said the people, who declined to be identified because the auction is private. AT&T, the second-biggest U.S. mobile-phone company, and U.S. Cellular Corp. also made offers, according to one of the people. The deadline for bids was last week.

The businesses for sale serve 2.1 million customers in more than 20 states and may fetch as much as $3.5 billion, said Hudson Square Research’s Todd Rethemeier. The U.S. Federal Communications Commission is forcing Verizon to sell the assets after the January purchase of Alltel made the carrier the nation’s largest mobile-phone company.

Verizon bought Alltel in January from the buyout arm of New York-based Goldman Sachs Group Inc. and TPG Inc. Basking Ridge, New Jersey-based Verizon spent about $28 billion for Alltel, which has about 14 million customers.

Spokespeople from KKR, Carlyle and Blackstone declined to comment, as did Verizon spokesman Peter Thonis, AT&T spokesman Michael Coe and Mark Steinkrauss, a spokesman for U.S. Cellular’s parent company Telephone & Data Systems Inc.

In February, Verizon said more than 30 parties had expressed interest in the assets. Carriers are jockeying for a bigger share of the wireless market as the pool of new subscribers shrinks. Phone companies have sold enough wireless devices to cover more than 80 percent of the U.S. population.

Verizon Communications Inc., which co-owns Verizon with Vodafone Group Plc, dropped 85 cents to $31.72 at 4 p.m. in New York Stock Exchange composite trading. The shares have declined 6.4 percent this year.

Blackstone Group LP, based in New York, is the world’s largest buyout firm, followed by Washington-based Carlyle. KKR, also in New York, is a private-equity company run by Henry Kravis and George Roberts.

To contact the reporters on this story: Serena Saitto in New York at ssaitto@bloomberg.net; Amy Thomson in New York at athomson6@bloomberg.net

Last Updated: April 7, 2009 16:26 EDT