There's a looming threat on the horizon for Vonage, who has now admitted that they have no technical workaround that will let them avoid infringing on Verizon's patents. While they currently are still allowed to operate, per the courts, eventually it'll come down to either them paying Verizon or even worse, such as shutting services down. They were initially full of hope, but now admit it may be impossible to change:

Vonage told customers not to worry as they were working on a technical fix to avoid infringing on the patents; a fix which they now admit is beyond them. They do say they are confident that they can win on appeal, but that that process could take two years and will cost a great deal of money: perhaps more than the company can afford, meanwhile they are applying to extend the stay on the injunction indefinitely.
Vonage isn't the end of the road for Verizon, either, who may decide to go against a number of other U.S.-based VoIP offerings. The outcome of the Vonage vs Verizon case may set the pace for VoIP in the U.S. for a long time to come.