Hi George
DO NOT initialize the ATA and plug it in the Ethernet as advised by Vonage at the beginning. That way the box will hit their server and download via TFTP a locked firmware (if not already installed on warehoused item).
This is the normal factory reset procedure:
From the FAQ
a) Take the phone off hook.
b) The red button on the top of the ATA-186 will illuminate.
c) Press the illuminating red button on the ATA and dial 322873738#. (The numbers spell FACTRESET# on the telephone)
d) Voice prompt will ask you to dial * to save changes you have just made.
e) Press * on your phone’s keypad.
f) Hang up the phone.
I have now heard that appearantly the most recent version of the Vonage package CANNOT be factory resetted. Hang on dslreports.com where the community discusses such issues.