In this study, an empirical analysis was conducted to specify when the diffusion of mobile phones reached the maturity stage across 215 countries and regions between 1990 and 2020. For this purpose, we employed the innovation diffusion model (Logistic model) based on Rogers’ S-curve theory. Our findings indicate that 209 countries reached the maturity stage, with the majority transitioning during the late 2000s to early 2010s. Income level analysis reveals that high-income countries have reached maturity as early as 2008, followed by upper-middle, lower-middle, and low-income countries between 2013 and 2014. Furthermore, the findings reveal substantial variation in diffusion saturation levels both among and within income groups, particularly within low-income countries. The period between the acceleration and maturity stages was shorter in middle and low-income countries compared to high-income ones, suggesting that mobile phone diffusion exhibits “leapfrogging” characteristics in terms of both saturation level and diffusion speed.