This is the first measurement campaign that takes place in Greece in order to assess the exposure levels in different microenvironments (offices, bedrooms, living rooms, schools). Due to the exponential growth in the use of wireless network devices, the aim of this work was to perform indoor measurements with the use of personal dosimeters. The measurement period was 3 d in each of the 40 different locations that were selected, both in the urban and suburban area of Thessaloniki, the second largest city of Greece. The measurements took place from 23 July 2010 to 19 January 2012. After processing the obtained data with the robust regression on order statistics (ROS) method, various statistical exposure quantities were calculated. Compared to similar measurement campaigns across Europe, a larger proportion of measurement data above the detection limit for specific frequency bands (at most 56% for the DCS Rx frequency band) was found. Furthermore, mean exposure levels in the mobile downlink frequency bands were higher than those in other studies (GSM Rx: 0.259 V m, DCS Rx: 0.131 V m, UMTS Rx: 0.12 V m), yet many times below the ICNIRP guidelines. On the other hand, maximum exposures were found to be of the same magnitude (GSM Rx: 0.38 V m, DCS Rx: 0.3 V m, UMTS Rx: 0.28 V m). These measurement results indicate that signals from mobile base stations are dominant in workplaces and schools, whereas wireless phones and computer networks play the leading role in home environments. While the former reach their maximum values during daytime, the latter have an observable increase in the evening after work hours.