chanisms, we can implement defense-in-depth. Next, we will look at UMA security. UMA security The security concerns of UMA are broadly as follows: Authentication Encryption UMA authentication has to rely on Subscriber Identity Module (SIM) or Universal SIM (USIM). SIM uses the A3/A5/A8 algorithms for security. USIM supports the F8/F9 (KASUMI) and MILENAGE algorithms as well. For encryption, UMA relies on Wi-Fi security and IPSec (https: //www.3gpp. prg/specifications/60-confidentiality-algorithms security gateway helps to overcome some of the security challenges of UMA. A security gateway provides the required confidentiality and data security for subscribers of FMA. The security gateway does this by using IPSec tunnels to encapsulate the call and its signaling data. When the user's handset roams between wireless and 5G, the security gateway assists in the authentication and registration of the user and their privileges. Next, we will look at some UMA-security-related work done by Cisco several years ago along these lines. See https://www.cisco.com/cdc_content_elements/flash/mobile_sols/ partners_site/pdfs/partners/kineto/CTIA_Tear_Sheet.pdf. Figure 15.14 shows how Cisco secured their UMA architecture using a security gateway. FMC security considerations Unlicensed Mobile Access Architecture A Secured Architecture for GSM/Wi-Fi Voice Services Key Protection Technologies for Malicious and Non-Malicious Threats: Firewall, Intrusion Prevention Malicious DoS Protection - Anomaly Detection - Protocol Features Signaling Non-Malicious DoS Protection AAA Server Gateway - Call Admission Control - Bandwidth Limits/Traffic Shaping Authentication/Business Logic GSM + Wi-Fi Wi-Fi Handset Access Point Packet SGSN/GGSN Packet Bearer Controller Circuit Security Gateway and VolP Peering Point Protection Media Gateway Encryption, Security, Routing Call Control Voice Bearer Figure 15.14 - Securing UMA Cisco provides an enhanced UMA security gateway to offer a layered defense-in-depth approach that protects VoIP communication. Fixed