One-way satmodems (DVB-IP modems ) use a return channel not based on communication with the satellite, such as telephone or cable.
Two-way satmodems (DVB-RCS modems, also called astromodems) employ a satellite-based return channel as well; they do not need another connection. DVB-RCS is ETSIstandardEN 301 790.
... town the population is spread out with 22.3% under the age of 18, 6.3% from 18 to 24, 31.0% from 25 to 44, 26.9% from 45 to 64, and 13.5% who are 65 years of ag ...