Metro riders should not expect to receive cellphone service throughout the agency's underground system next month, despite a federal deadline for Metro to have it completed by Oct. 16.

The transit agency says it and its cellphone partners won't be able to finish the work until Dec. 31, 2015, according to a memo obtained by The Washington Examiner. And it's going to "necessitate additional shutdowns of major portions of track" to complete.

Metro officials have been asking Congress for a reprieve from next month's deadline, which could jeopardize $1.5 billion in federal funding if missed.

The House has approved a short-term extension, passing language as part of an unrelated continuing resolution that extends the deadline until March 27, 2013. Congressional officials plan to seek a more permanent extension after the November election or in the early months of the new Congress, according to the office of Rep. Gerry Connolly, D.-Va.

The Senate has yet to approve it, though, and isn't expected to pick it up until at least late this week. Sen. Barbara Mikulski, D-Md., for one, supports the measure as a way to ensure continued dedicated funding for Metro safety, according to her office.

Metro has had Verizon service in its underground rail network since the 1990s. But a 2008 federal bill that provided Metro with $150 million in federal funding every year for 10 years required the agency to expand the service to other cellphone carriers. Metro signed a deal with four major carriers that would pay Metro $51.8 million over 25 years for access to the tunnels.

The funding act required the transit agency to have the 20 busiest underground stations wired by October 2009, which it did. But the act states that all work, including the wiring of the remaining 27 underground stations and 50.5 miles of tunnels, must be complete next month.

Metro officials have been mum on when the project would be done. General Manager Richard Sarles on Thursday referred questions to the cellphone companies. The memo is the first documented admission by the agency that it won't finish on time.

The memo said the project has been delayed by the agency's focus on safety since the 2009 Fort Totten crash. It also said the installation crews had to meet Metro's training requirements, which sometimes take longer than a year. And crews have been limited to times when Metro is not running trains or shutting down tracks for "urgent safety matters."

An additional issue, though it wasn't mentioned in the memo, has been the financial trouble of one of the key parties. Powerwave Technologies, which is helping install the service, filed an Securities and Exchange Commission note in August that said its ability to continue operating was in doubt. It announced Wednesday, though, that it received a $50 million credit line.