The newest cities are Buffalo, NY; Burlington, NC; Corpus Christi, TX; Gainesville, GA; Greensboro-Winston Salem, NC; and Wichita, KS, according to a spokeswoman.

AT&T has not declared average speeds for its LTE or HSPA+ network, which it also terms 4G, but says they are several times faster than 3G speeds. Verizon Wireless, which had a head start on AT&T, with LTE, and has put the average download speeds at up to 12 Mbps. _

Sprint is also planning to launch LTE this summer. AT&T, Verizon and Sprint have all announced LTE-ready smartphones, and all three are offering the new Samsung Galaxy S III, although Verizon's has not yet gone on sale in its stores.

AT&T on Monday also that on July 15 it will offer a pink-colored Lumia 900, a Windows Phone 7 device that is already offered in white, black and cyan. The pink Lumia 900 will sell for for $99.99 with a two-year service plan, the same as the other models, a spokeswoman said.

AT&T has plans to provide software updates for Lumia customers in coming weeks, the blog said.