User Registration
                                            The device provides a registration database for registering users. Only users belonging to a User-type IP Group can register with the device. User-type IP Groups represent a group of SIP user agents that share the following characteristics:
                                            
                                                
                                                
                                                
                                                
                                                    |  | ■ | Perform registrations and share the same serving proxy\registrar | 
                                            
                                            
                                                
                                                
                                                
                                                
                                                    |  | ■ | Same SIP and media behavior | 
                                            
                                            
                                            
                                                
                                                
                                                
                                                
                                                    |  | ■ | Same SIP handling configuration | 
                                            
                                            
                                                
                                                
                                                
                                                
                                                    |  | ■ | Same Call Admission Control (CAC) | 
                                            
                                            Typically, the device is configured as the user's outbound proxy, routing requests (using the IP-to-IP Routing table) from the user's User-type IP Group to the serving proxy, and vice versa. Survivability can be achieved using the alternative routing feature.
                                            The device forwards registration requests (REGISTER messages) from a Server-type IP Group, but doesn't save the registration binding in its' registration database.