restrictions. VideoGuard has been used by the BBC, ITV, and Channel 4 to restrict non-UK viewing, although in recent years these broadcasters have moved to broadcasting FTA on the more geographically restricted footprint of the Astra 2D satellite which is mainly, although not entirely, focused on the UK and Ireland. In some cases, encryption is still used on some versions of ITV and Channel 4 services where rights issues or a lack of capacity on the Astra 2D satellite are an issue. Many broadcasters choose to pair their cards, meaning that a paired (also called "married") card can be used only in a specific broadcaster-supplied STB, or by using the serial number from said receiver with one of the reverse-engineered solutions. In the case of Sky, all cards are married to a particular STB, although almost all non-premium channels will still allow viewing even if the box and card are not paired. Other channels, such as Sky's sports and movie channels, cannot be viewed unless the viewing card is being used in its specifically paired set top box. Reverse engineering VideoGuard is unusual in that legitimate external conditional-access modules are not available, the encryption system instead being built into the hardware and firmware of platform-supplied set-top boxes. However, several groups have managed to reverse-engineer VideoGuard to the point where a legitimate subscriber's card can be utilised in third-party receivers to decrypt those channels which that subscriber is authorised to view. A software CAM emulator exists for the Dreambox & Triple-Dragon Linux-powered satellite receivers, along with the Diablo, Dragon, Giga-Blue and T-Rex conditional-access modules. Some of the reverse-engineered solutions are unable to update the card, meaning the legitimate card needs to be returned to official Sky receiver for a few hours (or overnight) to be refreshed, or programmes will no longer decrypt. An example of a reverse-engineered solution that does support card updates is NDSCam. Sky 2009 card replacements As of late March 2009, BSkyB have begun issuing replacement NDS smartcards. These new cards are believed to close off the current software CAM loophole. Supported broadcasters Several other broadcasters than Sky or DirecTV around the world use the VideoGuard system, including: DirecTV (Latin America) Hot (Israel), Yes (Israel) Viasat (Scandinavia) Sky Italia (Italy) Sky Deutschland (Germany) Sky Brazil (Brazil) Sky Network Television (New Zealand) Foxtel (Australia) Airtel DigitalTV (India) Tata Sky & Hathway (DVB-C) (India) Astro (Malaysia) TrueVisions (Thailand) D-Smart (Turkey)