Phoenix Systems company develops Phoenix-RTOS operating system for IoT appliances. Along with additional communication stacks, (e.g. Phoenix-RIME, Phoenix-G3, Phoenix-802.15.4), metering libraries, metering applications and energy meter hardware reference designs it constitutes a foundation for fast development of next generation Smart Grid appliances. Since May 2018 Phoenix-RTOS is available on the open source BSD license (https://github.com/phoenix-rtos/). Phoenix-RTOS operating system starting from version 3 is based on microkernel architecture. Microkernel approach allows operating system to be scalable. It can be used either in small devices running on battery for several years (e.g. Smart Gas Meters) or in advanced devices such as Data Concentrators providing rich User Interface and advanced communication functions. Phoenix-RTOS has been already implemented in Data Concentrators, Smart Gas Meters and Smart Energy Meters. Phoenix-SEM is the application framework for smart energy meter development. Phoenix Smart Energy Meter Framework is field proven commercially available solution, already used in over 30 000 DCU (withmetering functionality) in Poland and 16 000 smart gas meters for Apator Metrix designed and certified initially for the Polish market. Software-defined approach enables fast development of metering application on low resources platforms and unique flexibility in terms of meter functionalities delivered to end-customer. Phoenix-DCU is the application framework for data concentrator development. Phoenix DCU Framework consists of data concentrator application responsible for the logic of data acquisition, built-in PRIME basenode implementation, DLMS/COSEM client and DCSAP (Data Concentrator Simple Acquisition Protocol) client. This efficient implementation supports up to 1 000 smart energy meters per DCU device and is currently used in about 35 000 DCUs installed in the Energa-Operator distribution network in Poland.