With regard to the GV numbers not ringing, I would try to delete them off of both OBi devices, then re-add them, letting it go through the new authentication procedure. Add the two numbers first to the IP phone, and see if they work, then add them to the 202 and see what happens.
Regarding Callcentric, it's rather involved to explain here, but this is a high-level answer:
Log into your Callcentric web account (their portal page). Go to the Extensions page:
https://my.callcentric.com/extensions.phpAdd a new extension. For example, if your CC number is 17771234567, then the extension can be 17771234567101. To make things easy, use the same SIP password as you used for the original number. This now becomes a separate SIP registration that can be customized to use on a separate device.
Next, go to the Call Treatments tab. Set up a call treatment for your inbound DID number. This will tell Callcentric to ring your two extensions (the original 1777 number is one extension, and 101 is the other).
I've attached a screenshot, showing one of my call treatments for a DID that I use as a forwarding phone from Google Voice to Callcentric, which then rings all of my various VoIP gadgets, each with its own extension.
You can get as fancy as you like with extensions and call treatments; call treatments are also great to send spammers to the "disconnected or not in service" message.
You can even use
nomorobo.com as one number to simulring, to dump robocalls. Just tell
nomorobo.com that you are using Vonage, since Callcentric isn't listed as one of their choices, then add the toll free number nomorobo gives you, as one of the destinations to ring on your call treatment.