Speakers: Sec, schneider Listening to satellites and decoding is fun. We show interesting stuff we found, and how you can get into it. The Iridium satellite system provides voice and data coverage to satellite phones, pagers and integrated transceivers over Earth's entire surface. It was built by Motorola over 15 years ago, and parts of it remain unchanged to this day. Last year we showed how to decode the unidirectional pager messages. Since then we can share our better understanding of some of the protocol but also show listening to the SMS-like bidirectional SBD communication channel.