Cellphone service will arrive at 30 additional subway stations in 2012, including Times Square and Rockefeller Center, broadening access to include much of Midtown, the firm conducting the improvements said this week.

Transit Wireless, which launched cell service in six stations on 14th and 23rd Streets in September, is working to extend cellphone access to the 30 new stations this summer. Construction is slated to begin in April, a spokesman said.

Among...