This chapter provides an overview of the key convergence technologies that offer many services from the network infrastructure point of view. After a short presentation of the next generation network (NGN) architecture, we deal with convergence technologies for third generation (3G) networks. This chapter also reviews technologies for 3G cellular wireless communication systems. Next, the third generation wideband code-division multiple access (WCDMA) standard has been enhanced to offer significantly increased performance for packet data and broadcast services through the introduction of high-speed downlink packet access (HSDPA), enhanced uplink, and multimedia broadcast multicast services (MBMS). Challenges in the migration to fourth generation (4G) mobile system conclude this chapter.