Washington ? Federal regulators voted Thursday to require that Internet phone service providers connect their customers to the same emergency 911 capabilities as callers with traditional services.

The Federal Communications Commission gave providers four months to comply. It was left up to the providers to determine how to meet the new requirement for the service, known as Voice Over Internet Protocol.

Failure to comply would subject companies to FCC enforcement actions, including fines and cease and desist court orders.

The 4-0 vote came after FCC Chairman Kevin J. Martin invited families affected by the inability to reach emergency response centers over Internet phones to tell their stories. A Florida woman described how her infant daughter died while she was unable to reach an emergency dispatcher through her Internet phone.

“By moving quickly, we will save lives,” said Commissioner Michael J. Copps.

About 1.5 million customers use the service, which is growing rapidly.

The commission’s order will take effect 120 days from its publication in the Federal Register. Officials said it would be 30 to 45 days before it is published. VOIP companies must provide the commission with a letter certifying their compliance by the deadline.

Under the order, VOIP providers must ensure that all 911 calls are routed to the caller’s local 911 operations center and must provide the emergency operator with the customer’s callback number and location, whether the call is being made from the customer’s home or elsewhere.

VOIP providers also must inform their customers by the 120-day deadline of the capabilities and limitations of the 911 service they are being provided. Connection to a 911 operator, for example, would not be possible for a VOIP customer in the event of a power failure or loss of Internet connection.