Metro riders will soon be able to carry their phone calls underground, thanks to hardware installations beginning this weekend that will enable Verizon Wireless, Sprint Nextel, AT&T and T-Mobile to provide coverage at Metro stations.

The installations will occur in phases, beginning at the 20 busiest stations, and are part of a $1.5 billion stimulus bill passed by Congress last year. The first 20 stations are expected to be outfitted with coverage by Oct. 16, according to the Metro Web site. The entire Metro system is expected to be completed by October 2012.

Currently only Verizon customers and Sprint customers who pick up the Verizon signal get service underground. For other users, the expansion may be spotty at first because the signal will only be available at the 20 stations, leaving the other 27 stations and tunnels without coverage.

The wireless signals will be provided from “large, cabinet-like enclosures that will house the hardware at the ends of station platforms or on mezzanines, in areas that will not impede the flow of customers or impact the safe operation of the Metrorail system,” according to a Metro statement.

The first 20 stations that will receive coverage  will be the Ballston-MU, Bethesda, Crystal City, Columbia Heights, Dupont Circle, Farragut West, Farragut North, Federal Triangle, Foggy Bottom-GWU, Friendship Heights, Gallery Place-Chinatown, Judiciary Square, L’Enfant Plaza, McPherson Square, Metro Center, Pentagon, Pentagon City, Rosslyn, Smithsonian, and Union Station stops.