A method for powering Voice over Long Term Evolution, VoLTE, in Long Term Evolution, LTE, networks, where a VoLTE-World Bridge, VoLTE-WB, supports VoLTE User Network Interface, UNI, and Network-to-Network Interface, NNI, functions, and carries out the following steps: a) centrally enabling a VoLTE/Voice over WiFi, VoWiFi, for a Carrier network lacking a full-fledged IP Multimedia System, IMS, core; b) enabling re-use of a standard 2G/3G Circuit Switched, CS, roaming call model for both signaling and media routing, and eliminating the use of a service route header for the routing of a mobile originating calls if a Home Public Mobile Network, HPMN, of a subscriber has also deployed a VoLTE-WB; c) routing a roaming signal towards an interface connection in line with said standard 2G/3G CS roaming call model; wherein the method is characterised in that the VoLTE-WB further carries out the following steps: d) using a Mobile Application Part, MAP, or S6a interface to retrieve authentication vectors from a 2G/3G/Evolved Packet Core, EPC, Home Location Register/Home Subscriber Server, HLR/HSS, enabling a re-use of currently deployed interfaces without requiring support, testing, validation or integration of a new interface on the HLR/HSS; e) integrating the VoLTE-WB with standard IMS networks and other VoLTE-WB networks to provide User Network Interface, UNI, and Network-to-Network Interface, NNI, capabilities to render national services, interworking, and roaming functionalities, by means of a lite Private Branch Exchange, PBX, capable of communicating on IMS SIP and Real Transport Protocol, RTP; f) tracking a radio network serving the subscriber through radio-access-type tracking, and selecting the terminating domain accordingly through the VoLTE-WB; g) implementing voice call continuity whenever the VoLTE subscriber in a call leaves LTE coverage in favor of 2G/3G coverage, by using a call back and call merge method. a) centrally enabling a VoLTE/Voice over WiFi, VoWiFi, for a Carrier network lacking a full-fledged IP Multimedia System, IMS, core; b) enabling re-use of a standard 2G/3G Circuit Switched, CS, roaming call model for both signaling and media routing, and eliminating the use of a service route header for the routing of a mobile originating calls if a Home Public Mobile Network, HPMN, of a subscriber has also deployed a VoLTE-WB; c) routing a roaming signal towards an interface connection in line with said standard 2G/3G CS roaming call model; d) using a Mobile Application Part, MAP, or S6a interface to retrieve authentication vectors from a 2G/3G/Evolved Packet Core, EPC, Home Location Register/Home Subscriber Server, HLR/HSS, enabling a re-use of currently deployed interfaces without requiring support, testing, validation or integration of a new interface on the HLR/HSS; e) integrating the VoLTE-WB with standard IMS networks and other VoLTE-WB networks to provide User Network Interface, UNI, and Network-to-Network Interface, NNI, capabilities to render national services, interworking, and roaming functionalities, by means of a lite Private Branch Exchange, PBX, capable of communicating on IMS SIP and Real Transport Protocol, RTP; f) tracking a radio network serving the subscriber through radio-access-type tracking, and selecting the terminating domain accordingly through the VoLTE-WB; g) implementing voice call continuity whenever the VoLTE subscriber in a call leaves LTE coverage in favor of 2G/3G coverage, by using a call back and call merge method. <EOS>