Kansas City, Mo. ? Sprint Nextel Corp. on Thursday increased the expected cost savings from its recent merger by $2.5 billion to $14.5 billion.

The nation’s third-largest wireless carrier, based in Reston, Va., with an operations headquarters in Overland Park, said Sprint Corp.’s acquisition of Nextel Communications Inc., was ahead of schedule. The figure includes taxes and about $1 billion in integration costs.

Sprint completed its $35 billion acquisition of Nextel last month, rolling out its new unified Sprint brand in a marketing blitz over the Labor Day weekend.

“We’re off to a great start,” Gary Forsee, the company’s president and chief executive officer, told analysts Thursday. “We did hit the sweet spot of the September time frame to launch the (merged) company.”

Breaking down the savings, the company said $1.6 billion would come from increased revenue from improved customer retention and from being able to sell Sprint services to former Nextel customers and vice versa.

An additional $3.7 billion would come from not having to duplicate network upgrades and from sharing cell towers; $4.4 billion would come from consolidating back office operations; $2.3 billion from smaller network operating costs; and $3.5 billion from savings tied to the company’s larger scale.

The company mentioned savings from “elimination of duplicate staffing” but didn’t give a specific number.

“We’re still not identifying an overall employee reduction for the company,” spokesman Scott Stoffel said. “It’s still premature to do that.”

Lisa Pierce, an analyst with Forrester Research, said she was curious to see the company’s strategy in sharing cell towers, noting that Cingular Wireless received complaints from former AT&T Wireless customers when their merger resulted in some areas no longer getting wireless signals.

Pierce also said Sprint Nextel’s fortunes would continue to be questionable until it resolved its fight with Nextel Partners Inc. and its other affiliates, some of whom already had been folded into the parent company.

“These synergies may be important, but we also have to ask the question of the settlement of the affiliates,” she said. “We may be saving money here but be spending money elsewhere.”

Forsee told analysts negotiations were continuing with affiliates.

Nextel Partners, which sells Nextel-branded services in 30 states, on Thursday said it would conduct a special shareholder meeting Oct. 24 to vote on whether to trigger a “put” provision that would force Sprint Nextel to buy the company’s outstanding shares.

Sprint Nextel already owns roughly a third of the Kirkland, Wash.-based affiliate.

Also Thursday, Sprint Nextel said it would spend $5.6 billion this year to upgrade equipment in the company’s network and about $900 million to begin switching Nextel’s push-to-talk service over to its new bandwidth. In 2006, the company will spend $6 billion on upgrades and about $1 billion on the bandwidth switch, expected to be completed in 2007.

The company added that for the third quarter, it expects to pick up an additional 1.2 million wireless subscribers, bringing its total to 45 million. It said the estimate includes about 1 million direct subscriber additions.

Sprint Nextel said it estimated 700,000 additional postpaid direct subscribers for the third quarter, crediting improving sales after the Labor Day launch of the new consolidated brand.

It also said demand was increasing for Boost Mobile prepaid services in the third quarter.

Patrick Comack, an analyst with Zachary Investment Research and Management of Miami Beach, said in a research note that the postpaid figures, which measure customers who pay a monthly bill as opposed to those paying for services upfront, was much lower than the 975,000 he had expected. He said the total could be a sign that Sprint Nextel’s customer sales division has been distracted by the merger or evidence of a general slowdown in the industry.

Meanwhile, the company said it’s long distance and local service divisions would be expected to report quarterly earnings in line with the company’s current guidance.

Shares of Sprint Nextel gained 76 cents, or 3.2 percent, to close at $24.31 Thursday on the New York Stock Exchange. The stock has traded in a 52-week range of $19.70 to $27.20.