Zero routers required - saves money to buy and install.
Less site maintenance visits, as these devices can work consistently on batteries for 5+ years or so.
GSM devices can work with 2 way (sending and receiving data simultaneously) or 1 way communication.
Devices can be connected to the main power supply or work on batteries for 5+ years. It can be installed almost everywhere without relying on routers, cabling and etc.
Works straight out of the box without any additional configuration needed. 10 years sim card data installed for your peace of mind.