CAMPBELL, Leith H. Whatever Happened to ISDN?. Journal of Telecommunications and the Digital Economy, [S. l.], v. 13, n. 2, p. 88–103, 2025. DOI: 10.18080/jtde.v13n2.1279. Disponível em: https://mail.jtde.telsoc.org/index.php/jtde/article/view/1279. Acesso em: 6 oct. 2025.