Hi cruzcartagena:
I don't believe Total Access gateways or SBCs can be used as a SIP registrar, as you would use a PBX. AOS includes a SIP registrar feature that is limited to support remote phones connecting through the firewall. See Remote Phone Configuration for AOS SIP Gateway for details and examples. This will accept SIP registrations from remote endpoints and pass on the corresponding registrations to a PBX, handling common challenges such as far-end NAT.
Best,
Chris
