rights management may be applied. A film that is chosen, for example, may be playable for 24 hours following payment, after which time it becomes unavailable. IPTV-based converged services Another advantage is the opportunity for integration and convergence. This opportunity is amplified when using IMS-based solutions. Converged services implies interaction of existing services in a seamless manner to create new value-added services. One example is on-screen caller ID, getting caller ID on a TV, and the ability to handle the call (send it to voice mail, etc.). IP-based services help to provide consumers anytime and anywhere access to content over their televisions, PCs, and mobile device, and to integrate services and content to tie them together. Within businesses and institutions, IPTV eliminates the need to run a parallel infrastructure to deliver live and stored video services. Limitations IPTV is sensitive to packet loss and delays. An IPTV channel has a minimum bandwidth requirement. Some systems are able to adapt to lower available bandwidth by reducing picture quality. Although a few countries have very high-speed broadband-enabled populations, in other countries legacy networks struggle to provide 3–5 Mbit/s and so simultaneous use of IPTV, VOIP and Internet access may not be viable. The last-mile delivery for IPTV usually has a bandwidth restriction that only allows a small number of simultaneous TV channel streams – typically from one to three – to be delivered. Latency The network delay inherent in the use of satellite Internet access is often held up as a reason why satellites cannot be successfully used for IPTV. In practice, however, delay is not an important factor for IPTV, since it is a service that does not require real-time transmission, as is the case with telephony or videoconferencing services. It is the delay of response to requests to change channel, display an EPG, etc. that most affects customers’ perceived quality of service. Existing video transmission systems of both analogue and digital formats already introduce known quantifiable delays. Existing DVB TV channels that simulcast by both terrestrial and satellite transmissions experience the same 0.25-second delay difference between the two services with no detrimental effect, and it goes unnoticed by viewers. Bandwidth requirements Digital video is a sequence of digital images, called frames, each made up of pixels or picture elements. Three bytes are typically used to represent the colour of the high quality image. Movies use 24 frames per second, North