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.