New York, NY
One more, CLID related feature, not described in the above mentioned FAQ, is there too - it's the one defined by RFC 3261 as "in-reply-to" header.
Shortly, if you use a SIP PBX and that PBX supports (or allows configuring) "in-reply-to" header for incoming calls which are forwarded to an outbound trunk - Callcentric will assign the same outgoing caller-ID to a call which had been received and is still active with a call-ID referenced by "in-reply-to" header.
This feature allows, in a standard way, and _without_ a prior made verification with a provider/carrier, to send out a call with the same Caller-ID as an inbound call made to your PBX by an external caller from PSTN or mobile line.
Now you may forward back to PSTN, a call made to your phone extension from PSTN or Mobile networks while preserving the caller's identity and most importantly - you don't need to verify your callers' CLIDs with Callcentric prior forwarding such calls back to PSTN or another [SIP] network.
A disclaimer for telephone SPAM'ers and SCAM'ers:
Attempts to spoof 3-rd party identities are considered illegal by FCC while prevention of such a spoofing is enforced at service providers; Callcentric uses all legally and technically possible means to identify and prevent caller-ID spoofing. Such measures may include a detection, isolation and immediate blocking of violating accounts. You've been warned.