Motorola Inc. moved Wednesday to freeze pensions and salaries, as well as take further steps to conserve cash as plummeting demand for handsets continues to take a toll on the wireless industry.

The Schaumburg, Ill., maker of telecommunications equipment, which is struggling to compete in both the low and high ends of the cellphone market, also said it would suspend contributions to employees' retirement savings plans, just weeks after announcing broad cost reductions and layoffs.

The...