SG 19 is the Lead Study Group on mobile telecommunication networks and for mobility. It is home to ITU's work on the network aspects of mobile telephony, including not only IMT-2000 which is ITU's global standard for third generation (3G) wireless communications, but also key aspects of the evolution of the core network infrastructure as radio access technologies evolve beyond IMT-2000 to support increasing broadband and mobile capabilities. The mobile aspects of telecommunications are an essential part of the rapidly emerging convergence of information, communications and telecommunications (ICT), especially given that mobile subscribers outnumber fixed subscribers in many markets, notably in developing countries. SG 19 is a key part of the ITU-T’s Next Generation Networks - Global Standards Initiative.

Particular attention is given to the convergence of mobile and fixed networks, the evolution of mobility management, globalization of regional 3G standards, and support for developing countries. The overall approach is to make the underlying technologies invisible to the user regardless of a multi-service, multi-protocol, multi-vendor, multi-operator, and increasingly hyperconnected environment. SG 19’s activities on third generation (3G) mobile networks means that it works closely with ITU’s Radiocommunication sector (ITU-R) which is responsible for the radio frequency spectrum and radio system aspects of IMT-2000; and ITU-D, which is responsible for studies, activities and direct assistance relating to the implementation of IMT-2000 in developing countries. Similarly, SG 19 also works with various other standards developing organizations (SDOs) including both the 3G Partnership Projects (3GPP and 3GPP2) and the Open Mobile Alliance (OMA).​