The activist investor Carl Icahn, who has pressured Motorola to break itself up, cautiously welcomed the company’s announcement that it would split into two separate publicly traded companies, spinning off an unprofitable mobile phone unit to investors.

Icahn said Wednesday that the move, which Motorola made after a two-month strategic review of its businesses, was “clearly a step in the right direction.” But he questioned Motorola’s commitment to moving quickly to solve its problems.

Gregory Brown, the Motorola chief executive, conceded that the main problem facing the company was its inability to come up with new products to replace the highly successful Razr, which once was a must-have cell phone but has faded from the scene. Brown said he hoped that by turning the mobile devices business into its own unit, the company would have better luck attracting a new chief executive to run it and revive Motorola’s reputation.

“I think the challenges around Motorola have been about consistent execution,” Brown said. “That is why it is so important for us to expand and improve our product portfolio.”

Motorola’s influence, and share price, have declined as rivals have taken the lead in interesting technology.

Apple, for example, has captured the attention of buyers in the high-end market with the iPhone. Executives of Motorola, which is based in Schaumburg, Illinois, declined to talk about what new telephones it planned to offer consumers in the coming months. Next week is a big one for the mobile phone business: top companies are gathering in Las Vegas for the industry’s largest U.S. trade show, CTIA Wireless 2008. Many will take the opportunity to unveil flashy new phones in the hope that consumers will snap them up during the next year. But when it comes to Motorola, expectations are low.

Cell phone production is the largest division of the company,…