In 1999, the International Permafrost Association (IPA) established the Global Terrestrial Network for Permafrost (GTN-P, gtnp.org). The goal of the network is systematic and long-term documentation of the distribution, variability, and trends of permafrost (an Essential Climate Variable, ECV) based on a global network of field measurements. The two current cryospheric indicators are permafrost temperature and active layer thickness, throughout the Earth’s permafrost regions. The network has been mainly operated by scientist and research institutions and programs. GTN-P developed a Data Management System (gtnpdatabase.org) for the collection, processing (including standardisation), and dissemination of permafrost data and metadata. Recent ground temperature and active layer thickness data are being compiled to provide an update to the current permafrost state. GTN-P is part of the Global Climate Observing System (GCOS) Global Terrestrial Observing System (GTOS). GCOS is a joint undertaking of the World Meteorological Organization (WMO), the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational Scientific and Cultural Organization (UNESCO), the United Nations Environment Programme (UNEP) and the International Council for Science (ICSU). Permafrost temperature measurements, commonly performed with permanently installed multi-thermistor cables in boreholes, enable a good accuracy of 0.1°C. The logger resolution and measurement frequency, however, varies with the type and the depth of the individual borehole. Due to high geomorphological surface and subground dynamics, the relative vertical position of testing probes can change and bias the depth indications of old boreholes in sensitive areas. Most important quality concerns are measurement accuracy, zero annual amplitude depth, data gaps, incomplete time series, and spatial clustering of boreholes. We developed a methodological approach to filter the data by defined quality rules in order to calculate global to regional weighted averages of permafrost temperature anomalies. In this presentation we aim to give an overview on the systematical data pathway from borehole principal investigators over National Correspondents in GTN-P, followed by data processing algorithms in the GTN-P DMS towards quality checked time series data.