When radio frequency microelectromechanical system (RF MEMS) based switches appeared more than 25 years ago, micromechanics has attracted huge attention for enabling near-ideal microwave devices. Since then, MEMS switches and circuits went through different development stages and are currently proving themselves commercially viable. Micromachining technology has the potential to become an enabling technology for microwave, millimetre wave to even sub-millimetre wave systems. The reliability of MEMS devices is one of the prime challenges to meet present state-of-the-art performances due to occurrence of multiple failure modes after few cycles of operations. The reliability becomes more critical when multiple MEMS switches operate simultaneously like in a higher order switching networks, multi-bit digital phase shifters or in a tunable filters. This Chapter presents detailed experimental studies on these devices considering life cycles up to 1 billion cycles of operation. A complete design guideline for reliable MEMS switches, phase shifter and filters are given for readers. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.