Earlier this month, Wal-Mart said it will sell discounted mobile services nationwide, threatening to aggravate a price war and hurt profit margins across the U.S. wireless sector.

RadioShack said third-quarter net income fell to $37.4 million, or 30 cents a share, from $49.1 million, or 38 cents a share, a year earlier. Analysts on average were expecting 31 cents a share, according to Thomson Reuters I/B/E/S.

Sales fell 3.1 percent from the year-earlier $1.02 billion.

The retailer, which has about 4,470 company-operated stores, almost 1,300 dealer outlets and over 450 wireless phone kiosks throughout the United States, said sales at its stores and kiosks open at least a year fell 2.9 percent.

While sales of converter boxes, laptops and wireless accessories fell, demand for Sprint Nextel postpaid wireless offerings, prepaid wireless handsets and netbooks was steady.

RadioShack's gross margin improved by about 0.9 percentage point to 47.6 percent as the retailer included more higher-margin products, such as postpaid and prepaid wireless plans, and moved away from lower-margin products like converter boxes, laptops and GPS.