AT&T Inc. has started marketing a high-speed Internet service called AT&T Business Fiber in multitenant office buildings in San Diego.

The carrier said that the new component of its U-verse service offers speeds up to 300 megabits per second, on uploads and downloads. Those speeds allow for advanced services such as large-scale data backup or videoconferencing. AT&T (NYSE: T) said it plans to eventually offer service at 1 gigabit per second.

AT&T has already introduced its Business Fiber service to 18 other markets. It said the service is not yet available for all building locations in San Diego.

Dallas-based AT&T reported revenue of $128.8 billion in 2013 and has not yet reported its 2014 financial results.