The FB2500 supports call recording by teeing off the two way audio from a call leg and sending to a SIP endpoint. The SIP endpoint will then record the call and handle it in any way you wish.
The recording is controlled by setting an email address on a call leg. This can be configured for telephone users and set to automatically record incoming only, outgoing only, or all calls. You can also set this on a hunt group to record all incoming calls to the hunt group (attaching the recording to the calling leg).
The recording server can be any SIP endpoint, such as an asterisk box. A linux based call recording app is available to FireBrick customers for this purpose, and some VOIP carriers may offer this as a service.