@George. Don’t get desperate. I purchased it in May and it was working. But hey, only lucky ones get something for nothing. We both knew the very low potential risk. If you didn’t want to take any risk, you would have called a local Cisco Distributor, selling the ATA186 for 150 USD or more.
My recommendation for you: Sign up with Vonage, cancel the membership after the free period and have them unlock your device after this. I guess there is no other way to protect your “investment” unless you can convince them to do it for nothing again after having given you 30% off ona device.