Geeeeeeeeeez. The posts are "old" because not much has changed since the thread began.
Callcentric offers different types of inbound service.
"IP Freedom" can only be used to make and receive calls between other Callcentric users, or other SIP users; it does not give you an inbound Public Switched Telephone Network (PSTN) telephone number.
Callcentric offers different inbound calling plans, either billed per-minute, or per-bucket-o-minutes, or unlimited, with PSTN phone numbers available in most locations. All inbound calling plans include CNAM. Some inbound plans require the extra $1.50/month for E911, and other plans bundle in E911 with the monthly fee.
Callcentric also owns its own Competitive Local Exchange Carrier (CLEC), Telengy. It offers free inbound PSTN numbers in the NY State area. These numbers are ideal as forwarding numbers for Google Voice, since nobody needs to know or call that number; it would only be called by Google Voice to forward your calls.
SO: your choice. Get a free NY DID, and pay the $1.50 fee for E911, if you'll only be using this for Google Voice, or, get a local DID if you'd like to use it as a full-function local phone number, or you can even port in an existing local number.