Once a request to port a number occurs there is no way the original telco can stop the transfer, if it was a wireline number it can take up to 30 days. If you cancel service with the new guys before the old guys can resign you and get your number back, you lose the number. Telco's if you are unhappy get very slooow about porting, especially if the magic day number hits a fee mark. Dunno if FCC handles voip, dont think so but complain anyway. Vonage is stenching uo the FCC as it is and they will quickly try to resolve your problem.
thanx,
bill