The problem was widely reported by AT&T customers in the area on Twitter, some of whom said they had not had voice, data or SMS (Short Message Service) capability for several hours. AT&T spokesman Mark Siegel said he did not have information about the length or geographic scope of the problem.

The outage came at an embarrassing time for AT&T, which has acknowledged coverage limitations in San Francisco and New York City that have generated many complaints. AT&T Mobility CEO Ralph de la Vega said earlier this week that the company is working hard to improve the quality of its service in those cities, according to news reports.

The failure did not affect the carrier's older, slower GSM (Global System for Mobile Communications) or EDGE (Enhanced Data Rates for GSM Evolution networks, according to Siegel.