Cellular-to-VoIP call establishment systems, methods, devices, and computer software

Various embodiments of systems, methods, devices, and computer software for establishing a cellular-to-VoIP call are provided. One embodiment is a method for establishing a VoIP media session between an originating cellular telephone and a VoIP destination device. One such method comprises: receiving a first data message from an originating cellular telephone, the first data message comprising an identifier associated with a VoIP destination device; sending a second data message to the originating cellular telephone, the second data message comprising information identifying a temporary directory number (TDN) associated with the VoIP destination device; detecting an incoming voice call to the TDN from the originating cellular telephone; sending an invite message to the identifier associated with the VoIP destination device; sending a ringing indication to the originating cellular telephone; receiving an accept reply from the VoIP destination device; and answering the incoming voice call from the cellular telephone and establishing a VoIP media session between the originating cellular telephone and the VoIP destination device.