revious mobile protocols. See Figure 7-7 for voice frequencies on VoLTE. High frequencies up to 7000Hz (think sopranos) are not cut off, and neither are lower frequencies down to 50Mz (think bass sounds). This results in clearer sounds in noisy locations. In short, www.TechnicalPDF.com users in noisy locations can hold clearer conversations on their LTE and 5G smartphones. www.TechnicalPDF.com High Definition Voice: High and low frequencies are not cut-off Noise cancellation strips out background sounds. Traditional Voice 300 to 3400 Hz High-Definition Voice 50 to 7000 Hz www.TechnicalPDF.com Figure 7-7 Voice frequencies on VoLTE (high- definition voice) compared to those without VoLTE. Accessing Applications and VoLTE-The IP Multimedia Subsystem IP Multimedia Subsystem (IMS) is a 3GPP open- standards architecture made up of multiple protocols and standards by which customers can access applications from many types of mobile devices. These applications include unified messaging and multiplayer games that are installed in a provider's network- connected platform. The signaling and control of IMS services are built around session initiation protocol (SIP), which is the signaling protocol used on IP networks such as the Internet for transferring traffic between carriers and for linking enterprise sites to IP networks. SIP signaling is used for functions such as setting up a video session (a call), tearing down the session, carrying numbers dialed and mobile devices' identity. For information about SIP, see the section "Session Initiation Protocol-Out-of-band Signaling" in Chapter 6. VoLTE is based on the IMS, IP Multimedia Subsystem standard. IP IMS is access independent. See Figure 7-8 for IP Multimedia System. Access independence refers to the fact that subscribers, for example, on Gigabit Ethernet, any mobile protocol, Wi-Fi, or cable modems can access IP-based applications such as video calling or chat services on the IMS network. In contrast to IMS's goal of universal access, specialized services such as WhatsA