Motorola Inc. is selling its wireless networks unit to Nokia Siemens Networks for $1.2 billion, a move that will accelerate the Schaumburg-based company’s planned break-up into separate businesses.

The deal, expected to close at the end of 2010, will boost Nokia Siemen’s standing in key markets such as the U.S. and Japan, while allowing Motorola to devote more attention to the enterprise mobility unit that makes communications equipment for public safety agencies and industrial companies.

“We talked to a few different potential acquirers, but Nokia Siemens made the most sense financially, strategically and from a people and culture standpoint,” Motorola co-Chief Executive Greg Brown told the Tribune in an interview.

Motorola said it expects about 7,500 employees in the U.S., China and India to transfer to Nokia Siemens when the deal is finalized. No layoffs are planned, Nokia Siemens Chief Executive Officer Rajeev Suri in a Monday conference call. About 1,600 people out of the 7,500 employees are based in Illinois and will be able to keep working locally, as Nokia Siemens has an office in Downers Grove.

Suri acknowledged that many Motorolans have a strong connection to that company’s culture.

“But I believe we can offer them a compelling alternative and, in fact, a compatible alternative – - different to be sure, but just as good,” Suri said.

Motorola is keeping $150 million in accounts receivable. It is also retaining its iDEN business, which makes a proprietary technology used by Sprint for the carrier’s Nextel push-to-talk network. The iDEN business represents about $400 million in annual revenue.

In addition, Motorola is hanging onto “substantially all” patents related to its networks business, with the deal giving Nokia Siemens a cross-license to access that intellectual property portfolio.

Motorola was already preparing to split into two independent, publicly traded companies in the first quarter of 2011. The mobile phone and television set-top box units will form one company called Motorola Mobility under the leadership of co-Chief Executive Sanjay Jha. The enterprise mobility and networks businesses were to form the other company, called Motorola Solutions and headed by Brown.

Motorola Solutions will now consist of just enterprise mobility. In the conference call, Brown said the sale of networks will allow his team to “further sharpen the strategic focus of our remaining Motorola Solutions business.”

Brown said during the call that he is not working on any more divestitures, indicating that Motorola will not be conducting further asset sales before the separation in early 2011.

The networks business was profitable in 2009, earning $366 million even as sales dropped to $4.1 billion from $5.2 billion in 2008. Brown had said his goal with the networks unit, which lacked the scale of Nokia Siemens and other rivals such as Huawei, was to manage the business for cash and earnings. In contrast, enterprise mobility was the best-performing unit at Motorola in 2009. It posted net earnings of $714 million on sales of $7 billion.

Brown acknowledged these differences between enterprise mobility and networks, saying during the call that keeping the two units together had somewhat muddied “the investment story” for the company. Now, with enterprise mobility left on its own, the post-split Motorola Solutions company is a “pure play” for investors, he added.

Meanwhile, Nokia Siemens said it expects to retain its No. 2 position in the global wireless networks infrastructure industry, while capturing the top position in Japan and rising from No. 5 to No. 3 in the U.S. The Motorola acquisition gives Nokia Siemens a bigger foothold with important U.S. carriers such as Sprint and Verizon Wireless.

The two companies said they are also “exploring a global relationship” in public safety, which would link Motorola’s enterprise mobility business with Nokia Siemens. Such a partnership would not fully come to fruition for several years, as it is dependent on rolling out fourth-generation wireless network technology called Long-Term Evolution, or LTE.

“It’s embryonic and we have many things to work through,” Brown told the Tribune.