University of Isfahan International Economics Studies 2008-9643 52 1 2022 09 01 Nonlinear Threshold Effect of Telecommunications Infrastructure Development on Economic Growth in D8 Countries: Panel Smooth Transition Regression (PSTR) Model 11 24 30022 10.22108/ies.2024.139275.1150 EN Fahmideh Fattahi Ph.D in Economics, Department of Economics, Faculty of Economics and Management, Urmia University, Urmia, Iran Hassan Khodavaisi Associate Professor of Economics, Department of Economics, Faculty of Economics and Management, Urmia University, Urmia, Iran Journal Article 2023 09 28 This study explores the impact of telecommunication infrastructure development on economic growth in D8 countries from 2007 to 2022. A panel smooth transition regression (PSTR) model is utilized to analyze this relationship. The chosen transition variable is the information and communication technology (ICT) index. The findings indicate a nonlinear association between the variables examined. The estimated threshold for the logarithm of the transition variable is 4.4433. Moreover, the results demonstrate that gross capital formation and urban population have a positive and significant effect on economic growth in the first regime. Conversely, financial development has a negative and significant impact on economic growth in the first regime. Furthermore, the results reveal that the urban population continues to have a positive and significant influence on economic growth, although its impact is lower compared with before. Additionally, financial development has a positive and significant effect on economic growth in the second regime.   <strong>JEL Classification: </strong>O40, O33, C23. https://ies.ui.ac.ir/article_30022_c98f7da78b81d54c361078fdac22898d.pdf