AT&T uses the Ericsson Mediaroom platform to deliver U-verse TV via IPTV from the headend to the consumer's receiver, required for each TV. Transmissions use digital H.264 (MPEG-4 AVC) encoding, compared to the existing deployments of MPEG-2 codec and the discontinued analog cable TV system. The receiver box does not have a RF tuner, but is an IP multicast client that requests the channel or "stream" desired. U-Verse TV supports up to four/six active streams at once, depending on service tier. The system uses individual unicasts for video on demand, central time shifting, start-over services and other programs.