No. This is in the terms of service from companies such as Vonage:
"Remember that our 911 Dialing service will not function in the event of a broadband or power outage or if your broadband, ISP or Vonage phone service is terminated."
Verizon is only required to privide battery backup of the "copper" Pots system and therefore offers a BBU that will enable voice to transmit/recieve over the fiber in case of power outage.
Written by Jeroen van der Maat
Last updated on 10.25.06