Microelectromechanical-systems technology (MEMS) applied to radio frequency (RF) and microwave systems (i.e. RF-MEMS) has recently started to exhibit its market potential in applications centred on telecommunications and consumer segments. As evolution towards the 5G (5th generation of mobile communications) and the Internet of things (IoT) is progressing, more agile, reconfigurable and multi-functional RF passive components and networks will be necessary. In this work, an entirely RF-MEMS-based impedance matching network (IMN) is reported and discussed, taking the global system for mobile communications (GSM) protocol as testing scenario. The mentioned RF-MEMS IMN was designed in order to perform proper impedance conversion between a CMOS class-E power amplifier (PA) and the transmitting/receiving antenna of a GSM system. In the following pages, the RF-MEMS IMN will be discussed in details against its design solution, working principles, as well as electromechanical and RF simulated and measured characteristics.