EXHIBIT 22 The subsidiaries of American TeleSource International, Inc. are as follows: State or other Company Jurisdiction of Incorporation ---------------------- ----------------------------- American TeleSource International, Inc. Canada American TeleSource International, Inc. Texas American TeleSource International de Mexico, S.A. de C.V. Mexico GlobalSCAPE, Inc. Delaware Sistema de Telefonia Computarizada, S.A. de C.V. ("Computel") Mexico Servicios de Infraestructura, S.A. de C.V. ("Sinfra") Mexico TeleSpan, Inc. ("TeleSpan") Texas ATSI de CentroAmerica, S.A. Costa Rica