It appears that you don't have a clear understanding on how any of this works.
Google Voice is a call forwarding service. When someone calls your inbound Google Voice phone number, Google Voice will forward that call to the destinations you select. You can select to have all calls forward only to VoIP clients (your web browser, your Android or iOS Google Voice mobile apps, and/or your OBiTALK device). These are all SIP calls. Optionally (either instead of, or in addition to SIP), you can forward calls to regular 10-digit US phone numbers, in addition to, or instead of, to SIP clients.
IF you want to use Callcentric, then you will a) go into Google Voice settings and DISable forwarding to your mobile phone(s)' Google Voice apps, and b) ENable forwarding to the Callcentric number, to pick up CNAM.
This setting is separate from outbound calling. You will still make outbound calls via Google Voice, either from your web browser, or your OBiTALK device, or your mobile phone apps. As a backup, IF you properly subscribe to Callcentric service plans, you can also call out directly from your Callcentric number as a backup.
Callcentric sells inbound calling, outbound calling, and 911 service a la carte.
The absolute minimum needed would be to subscribe to their "dollar unlimited" INbound service, which will become your "detour" for inbound calls to pick up CNAM, and to subscribe to their 911 service (remember, 911 calls are outbound calls) for $1.50/month. That totals $2.50/month. Optionally, instead of the $1.5o/month charge for 911 service, subscribe to the "North America Basic" OUTbound plan, which includes the 911 service AND 120 minutes of outbound calling, that you can either ignore, or you can use in case Google Voice is temporarily not working.
Taoman's comment about number spoofing simply means that, IF you subscribe to CC's outbound calling plan, you will be issued a Callcentric phone number. By default, outbound calls made on that service will display your CC number's caller ID. Optionally, you can go into CC's settings and tell it to substitute, or "spoof" your Google Voice's phone number as the outbound caller ID.