America television uses approximately 30 frames per second where the Europe television frame rate is 25 frames per second. Each digital video has dimensions width and height; SDTV is pixels, HDTV uses up to pixels. There is no absolute answer for the bandwidth requirement for the IPTV service. Currently compressed HDTV content can be delivered at a data rate between 8 and 10 Mbit/s, but if the home of the consumer equipped with several HDTV outputs, this rate will be multiplied respectively. Privacy implications Due to limitations in bandwidth, an IPTV channel is delivered to the user one at a time. Changing a channel requires requesting the head-end server to provide a different broadcast stream, much like VOD. This could enable the service provider to accurately track each and every programme watched and the duration of watching for each viewer. In conjunction with regulatory differences between IPTV and cable TV, this tracking could pose a threat to privacy according to critics. For IP multicast scenarios, since a particular multicast group (TV channel) needs to be requested before it can be viewed, the same privacy concerns apply. Vendors Global sales of IPTV systems exceeded US$2 billion in 2007, although only a small number of companies supply most current IPTV system solutions. Some, such as Movistar TV, was formed by telecoms operators themselves, to minimize external costs, a tactic also used by PCCW of Hong Kong. Some major telecoms vendors are also active in this space, notably Accenture (Accenture Video Solution), Alcatel-Lucent (sometimes working with Movistar TV), Ericsson (notably since acquiring Tandberg Television), Huawei, NEC, PTCL Smart TV, Sri Lanka Telecom, Thomson, and ZTE, as are some IT houses, led by Microsoft. Miami-based AlphaOTT, Tokyo-based The New Media Group, Malaysian-based Select-TV, Oslo/Norway-based SnapTV, and California-based UTStarcom, Inc. also offer end-to-end networking infrastructure for IPTV-based services, and Hong Kong-based BNS Ltd. provides turnkey open platform IPTV technology solutions. Hospitality IPTV Ltd, having established many closed network IPTV systems, expanded in 2013 to OTT delivery platforms for markets in New Zealand, Australia, and the Asia Pacific region. Google Fiber offers an IPTV service in various US cities which includes up to 1 Gigabit-speed internet and over 290 channels depending on package via the fiber optic network being built out in Kansas City Kansas and Kansas City Missouri. Many of these IPTV solution vendors participated in the biennial Multiservice Switching Forum Interoperability 2008 (GMI) event