e Signal Received Quality Registration-Termination-Answer Real-time Transport Protocol Registration-Termination-Request Redundancy Version Server-Assignment-Answer Server-Assignment-Request SCC AS Service Centralization and Continuity AS SC-FDMA Single Carrier Frequency Division Multiple Access S-CSCF Serving-CSCF Service Data Flow Session Description Protocol Service GPRS Support Node System Frame Number Serving Gateway System Information Block SIGTRAN Signalling Transport over IP Single Input Multiple Output Session Initiation Protocol SIP-I SIP with Encapsulated ISUP VoLTE and ViLTE SI-RNTI System Information RNTI Single Input Single Output Subscription Locator Functional SM-AL Short Message Application Layer SM-CL Short Message Control Layer SM-RL Short Message Relay Layer SM-TL Short Message Transport Layer Short Message Service SMS-SC SMS Service Center Subscribe-Notifications-Answer Subscribe-Notifications-Request Subscription Profile Repository Semi-Persistent Scheduling Signalling Radio Bearer Sounding Reference Signal Signalling System 7 Secondary Synchronization Signal Session-Termination-Answer S-TMSI Shortened-TMSI STN-SR Session Transfer Number for SRVCC Session-Termination-Request Super Wide Band Timing Advance Tracking Area Identity Telephony Application Server TC-RNTI Temporary Cell RNTI Time Division Duplex List of Abbreviations xxvii Time Division Multiplexing Tunnel Endpoint Identifier Topology Hiding Interconnect Gateway Terminating Identification Presentation Terminating Identification Restriction Transparent Mode Temporary Mobile Subscriber Identity Transmit Power Control Transit and Roaming Function Transition Gateway Transmission Time Interval User Agent User-Authorization-Answer User Agent Client User-Authorization-Request User Agent Server Uplink Control Information User-Data-Answer User-Data-Request User Equipment Universal Integrated Circuit Card Update-Location-Answer Update-Location-Request UL-SCH Uplink Shared Channel Unacknowledged Mode Universal Mobile Telecommunications System U