This book presents the architecture of two networks that make up the backbone of the telephone service VoLTE and video service ViLTE. The 4G mobile network makes it possible to construct bearers through which IP packets, containing either telephone signals (SIP, SDP) or voice or video media (RTP stream), are transported. The IMS network performs the processing of the telephone signal to provide VoLTE and ViLTE services, including call routing...