AT&T Inc said some New York customers had voice service outages on Thursday morning because of a software problem that occurred during "routine maintenance activities."

The No. 2 U.S. mobile provider, which has long been criticized for service problems in the city, said mid-morning that it had fixed a problem which caused voice service disruption for some customers in the three city boroughs of Brooklyn, Queens and Manhattan and in neighboring Long Island.

Earlier in the day, AT&T had sent a statement saying only that it had problems with its third generation (3G) voice network in Long Island.

The company, which is looking to become the biggest U.S. wireless provider through an acquisition of T-Mobile USA, said it had moved some voice customers on its 3G network to its older second generation (2G) network to restore their service while it worked on the problem.