yes, but I think the gateways will limit your sms sends. They won't permit you to spam anyone, and surely limit how many you can send in some preset time period. His device has a radio and SIM card, so it connects to the provider network directly.
Actually, he'd be more successful if he marketed it differently. The device seems like it can be used with a number of home and business burglar alarms, to initiate an SMS message to the homeowner's phone or business owners phone when an alarm is triggered. I know these types of devices exist already, but perhaps he can make it cheaper than what can be bought from the professionals...
The problem is the big professionals don't like anything they didn't sell you and install themselves.