yes-- the Vonage "softphone" is designed so that you can talk (using a USB phone) with just a broadband connection and without the phone adapter...

so-- if you travel and don't want to bring your phone adapter stuff, you can use Vonage through your laptop... of course, they charge you $10/month extra for that convenience.

I have Vonage, and would really like the softphone functionality--- BUT, it doesn't seem worth it to spend the money... so I just bring my phone adapter with me when I travel.