1. [1] CTIA, https://www.ctia.org/national-spectrum-strategy, accessed Feb. 10 2021.
2. [2] 3GPP TS 23.228, IP Multimedia Subsystem (IMS) statge 2, 2011.
3. [3] 3GPP TS 33.203, Access security for IP-based services, 2011.
4. [4] 3GPP TS 33.210, Network Domain Security (NDS); IP network layer security, 2011.
5. [5] Huawei, Vo5G Technical White Paper, 2018.