They have some information about the frequencies stuffed at the bottom of their FAQs. One omission that bugs me is that they don't tell you the location of the ground stations, which can be a dealbreaker for whether or not this is effective
"You can connect with any satellite in low Earth orbit (LEO) and medium Earth orbit (MEO) operating in X-band and S-band frequencies, including: S-band uplink and downlink, X-band narrowband and wideband downlink."