Viaccess PC2.4 is a Conditional Access System developed by France Telecom. Along with its successor, Viaccess PC2.5, it is often refered to as Viaccess 2. It is one of five Viaccess systems in use to protect Digital Media Broadcast (DMB) content from unauthorized viewing. Viaccess PC2.4 replaces the insecure Viaccess PC2.3 Conditional Access System, but it was itself, in time, compromised, allowing for hackers to develop software modifications for receivers to decrypt the channels without paying any subscription fees.
It's predecessor had the same security problems, but was developed further into two modicationcs, TPS-Crypt and ThalesCrypt, which means it's use is still common among providers today. The Viaccess systems are used with providers around the world, being the third largest Conditional Access System for digital television content in use.