Vonage adapters sold on ebay aren't any good unless they are brand new or completely unlocked. I know this from experience, Vonage will send you a brand new adapter for free rather than let you use one that was used. I don't know why this is, but Vonage will not let you use a used adapter. So, in summary, don't waste your money unless it is brand new or unlocked. If you know how to unlock them, go ahead. Hope this helps!!