Question 23/XVIII - Guidelines for implementing ISDN field trials in developing countries Considering (a) the need, in particular for developing countries, for guidelines on field trials of ISDN systems and associated networks and terminals; (b) that administrations need to have a defined period together with a defined set of parameters for embarking on the field trial of ISDN capabilities and demand requirements; (c) the impact of ISDN on future network planning; the following points should be specially addressed: 1. What parameters influencing the field trial period for ISDN should be taken into account in drawing up guidelines? 2. What guidelines are required for the steps to be taken by administrations during the ISDN field trial period? 3. What guidelines are required for the trial methods and parameters influencing the said objectives? Note - This Question should be studied in consultation with other Study Groups, such as Study Groups II, IV, XI and XV.