AT&T has agreed to provide wireless service to every underground subway station, making it the second carrier to make the commitment.
Currently, there is wireless service from every major carrier except Sprint in the initial 36 stations of the MTA's plan to wire all 278 underground stations by 2017.
The second phase, which will be completed by the end of the summer, will increase the number of stations with wireless by 40, covering midtown Manhattan and Queens locations.
"The ability to make and receive phone calls underground is an important improvement for safety and security as well as convenience, and our customers will certainly appreciate it," MTA chief Thomas Prendergast said in a statement.
Sprint was first to agree to provide service to each underground station, but the company is still installing equipment, according to Transit Wireless, the company covering the cost of station wireless along with the carriers.
In the meantime, the company is negotiating contracts with the other providers -- Verizon and T-Mobile -- for the full build-out of underground station wireless, according to a spokeswoman.