Ann: SAS Completes World First Phone Calls, Instant Messaging, page-142

I've worked on communications networks and what you say is mostly true, but does not totally apply to SAS. Firstly the intended market is not voice calls, but lower priority services such as SMS, IM, M2M, IoT ect. Most SAS devices will talk direct to the satellite constellation (it in a low orbit remember) or to something that does. Some services will need to go via a ground station onto existing communications infrastructure, but if they have existing infrastructure they wouldn't be using SAS.