In a system and method for establishing communications in a communications network, a network service provider can assign IP addresses to mobile devices dynamically to conserve IP address resources. A network service provider can also implement network address translation to further conserve IP address resources and to provide improved security. If a requestor seeks to obtain an IP address of a mobile device and the address is a local address, the system determines if the mobile device has a network address translation (NAT) binding that associates the IP address of the mobile device with a public IP address. If the mobile device does not have a NAT binding, the system creates a NAT binding that associates the IP address of the mobile device with a public IP address.