Ericsson, the largest maker of equipment for mobile-phone networks, will post its first quarterly loss in nine years as phone companies cut spending and handset sales drop. The Swedish company forecast a first-quarter pretax loss of $406 million to $508 million, with sales unchanged or somewhat lower than a year earlier. In January, Ericsson said it would break even and sales would rise 15%. Ericsson and rivals such as Motorola Inc. are suffering amid slackening mobile-phone sales, reduced spending on networks and a weaker U.S. economy. Ericsson, which is farming out phone production to stem losses at its handset unit, said cellular-phone sales will fall considerably this quarter.