Prior to LTE, IMS did not gain significant momentum, with VoLTE however IMS is been designed to couple with LTE in order to create an environment capable of supporting voice traffic in a shared packet data network. The IMS being the call control system that is recognized the need for special network conditions required to support voice traffic. LTE may then be considered the call path system that is responsible for carrying out the IMS' call setup and tear down instructions. For VoLTE, IMS directs LTE to establish the desired QoS environment, then commence with the voice call. IMS also notifies LTE when the call has completed, and directs LTE to tear down the special voice environment