A federal appeals court on Tuesday refused to delay new Federal Communications Commission guidelines requiring Internet telephone companies to provide reliable 911 emergency call service.

The U.S. Court of Appeals for the District of Columbia denied a motion filed two weeks ago by a group of Internet telephone companies who claim the regulations are unreasonable.

In May, the FCC ordered providers of Internet-based phone calls – sometimes called Voice Over Internet Protocol, or VoIP – to certify that their customers will be able to reach an emergency dispatcher when they call 911. Dispatchers also must be able to identify the caller’s phone number and location.

The companies were given until Nov. 28 to comply. Companies that don’t meet the deadline will have to discontinue marketing Internet call service.