There are a few differences in the feature set on the FB9000 compared to the FB6000.
The FB9000 cannot currently act as a SIP PBX (this was a feature of the FB6502). The FB2900 can be used for SIP, but if this is insufficient for you do get in touch to discuss your requirements.
The FB9000 requires an activation key to support GTP, if this is something you're interested in please get in contact.
