Metro can begin asking companies to submit proposals to build an underground wireless network that finally would give all riders cell phone service, a board of directors committee decided Thursday.

But board members were dissatisfied with staff’s suggestion to allow the company that builds the system to determine how much to charge the other wireless networks to use it, fearing that astronomical rates could deter the other companies from the deal.

"We have no provision to prevent a monopoly, if it should occur," Finance Committee Chairman Peter Benjamin said.

While one wireless provider would shoulder the cost of building and operating the network, the committee determined that any proposal should spell out the rate the company would charge other wireless providers.

Riders have long complained that only Verizon Wireless customers have cell phone service underground.

Metro’s current wireless system was built by Verizon and is compatible only with Verizon and Sprint cell phone technology.

AT&T and T-Mobile users are unable to get cell phone signals while riding in Metro tunnels, and Sprint users can only access signals while roaming.

The comprehensive network being proposed would support cell phone service, WiFi and future Metro operations radios, as well as police and fire department radios.

It also would support the Metro Channel, the agency’s planned project to install flat-screen televisions displaying real-time customer information and advertising in trains, buses and stations.

The network would be available at 20 of the agency’s highest-priority stations within 18 months of awarding the contract, Chief Information Officer Suzanne Peck said last month.

"Congress is very eager for [this]," she said.

Wireless would be available throughout the entire system within four years, Peck said.