[Serusers] SER and Routing Help Question

Hello, maybe someone can help me with the routing. here the schema. Firewall with 3 Network interfaces 2x interfaces intern 1x interface extern the default provider is sipgate.de. ser shoult route all registration default to sipgate and listen on 2 intern interfaces. ser shoult handel all intern calls and route direct intern. user auth i'dont need or radius i'dont need. all inbount calls from extern shoult route automatic to right sip- phone. current i use the default configuration with 2 options more. listen 212.21.68.62 listen 212.21.69.110 maybe someone can help me to with the routing thanks a lot for your time, if you can help me. regards mario roeber