Universal Mobile Telecommunications System Wireless communication systems 23 Mobile communication systems 17 Global system for mobile communications 16 Quality control 10 Long-Term Evolution (Telecommunications) 9 Standards 7 Cell phone systems 6 Message processing 6 Telecommunication 6 Wireless LANs 6 Security measures 5 Management 4 Asynchronous transfer mode 3 Digital communications 3 Long-term evolution (Telecommunications) 3 Packet switching (Data transmission) 3 Planning 3 IEEE 802.11 (Standard) 2 Radio frequency allocation 2 Code division multiple access 1 Computer network protocols 1 Session Initiation Protocol (Computer network protocol) 1