Sensaphone (http://www.sensaphone.com), Ashton, PA

In business since 1985, family owned.  Poor website, no prices, must call company to order.  Gateway connects to your router.  The portal is on the gateway not the cloud; no mobile device access.  Gateway issues email/text message/voice call alerts via router.  Only ag sensors are temperature and humidity.  Gateway can handle up to 30 sensors, but each group of 7 requires a "router" (repeater).  Routers are sensors set to be such and require constant power.  Uses the shorter range frequency 2.3 GHz.  Would be useful in a situation where  you have a lot of freezers/coolers in fairly small area.