Satellite communications is a promising medium for multicasting services such as streaming media delivery. However, most of the current satellite multicasting systems use a star-type network with one transmitting earth station called a bub, which is generally located in an urban area. Therefore, it is difficult for small businesses located in rural areas to send their contents by using satellite multicasting network. To meet these demands, we developed the direct-multicasting satellite communications system (DMSCS), which can provides a full-mesh type satellite network easily and cost-effectively. DMSCS uses our newly developed multi-carrier/multi-rate modem called the group modem and a highly effective channel assignment control program. The group modem is an FDMA (Frequency Division Multiple Access) modem. It is composed of a control module, user interface modules, a multi-carrier/multi-rate modem (MCMRM) module, and IF up/down-converter module. Its features include simultaneous connections with 32 different points, communication at an arbitrary rate, and the use of a dispersed and discontinuous spectrum. The highly effective channel assignment control program is the operation program for DMSCS. It has scale flexibility and high functionality. This paper described the features of DMSCS, the architecture and performance evaluation of the group modem, and example of new services making the best use of the advantages of DMSCS.