Official 16. The Service Licensee shall: (a) comply with a frequency spectrum plan assigned and approved under this Law; (b) obtain permission and Service License again in accord with the provisions contained in Chapter III, if he desires to expand and provide any Telecommunications Service for which he has not yet obtained license, or to operate a joint venture or consortium with another licensee; (c) comply when directed to make necessary modifications or to temporarily suspend provision of any service based on the finding of an inspection or a notice that it is causing technical interference to another Telecommunications Service. 17. The Service Licensee shall maintain securely the information and contents that are transmitted or received through his Telecommunications Service and confidential personal information of each individual users, and shall not disclose and inform to irrelevant person except where allowed in accord with the existing laws. 18. The licensee of the Telecommunications Equipment shall: (a) keep and use the Telecommunications Equipments belonged to him only at the location specified in the license; (b) take measure not to affect the national security through the Telecommunications Equipment that he is allowed to use under the license; (c) comply with the directives by the Department with regard to the equipments used by him. 9