Motorola is in the early stages of seeking buyers for the unit, whose suitors include private equity firms and other communications equipment makers, said one source familiar with the situation.
Motorola may decide to keep the unit in the end, said the source, who was not authorized to speak with the media.
J.P. Morgan Chase & Co and Goldman Sachs Group Inc are advising Motorola on the possible sale, the source said.
J.P. Morgan and Goldman Sachs declined to comment.
Motorola, which has been losing market share in its cellphone business for years, declined to comment, but said it was still focused on its previously stated plan to separate its handset business from the rest of the company.
Analysts said there could be a lot of interest in the home and networks unit, particularly because Motorola has a strong market share in the set-top box segment, where it is bigger than Scientific Atlanta, owned by Cisco Systems Inc
But RBC analyst Mark Sue said that a divestiture of any of Motorola's other business units could hurt Motorola's money-losing handset business.
The mobile devices business still needs the rest of the businesses to fund its operations. It hasn't really recovered fully yet so it would be a little too early to cut off the lifeline, Sue said.
While growth in the mobile network equipment market has slowed dramatically in recent years, rival gear makers could see Motorola as a way to increase their market share, particularly in the United States.
Avian Securities analyst Matthew Thornton said a $4.5 billion price tag would represent an 18 percent premium over his estimated valuation of $3.8 billion for the home and networks unit, based on operating earnings.
Analysts at Avian Securities said that their sum-of-parts analysis values Motorola's Home & Networks Mobility Division segment at $4.25 billion, according to an emailed report.
Simply put, the deal price cited ... is not far off from our valuation, the report said.
Potential suitors could include Ericsson
The Wall Street Journal cited China's Huawei Technologies Co Ltd
The Wall Street Journal cited potential suitors as Silver Lake Partners
TPG declined comment and Silver Lake Partners was not immediately available for comment.
Motorola spokeswoman Jennifer Erickson said the company does not comment on rumor or speculation.
Separation into two independent, publicly traded companies (Mobile Devices and Broadband Mobility Solutions, which comprises Enterprise Mobility Solutions and Home and Networks Mobility Solutions) is the publicly stated long-term goal of Motorola, Erickson said. We remain committed to the separation goal and continue to believe that it is the right strategy to position Motorola for long-term success.
Motorola shares were down 15 cents, or 1.7 percent, at $8.70 in afternoon trading on New York Stock Exchange.
(Reporting by Sinead Carew, Jessica Hall and Megan Davies in New York; Editing by Andre Grenon, Tim Dobbyn, Gary Hill)