d) Does not impose unnecessary costs on number users; e) Is technologically neutral, in particular permitting evolution to new technologies and services; f) Is consistent with any applicable international treaties, commitments, recommendations or standards legally binding on Timor-Leste, including those of the International Telecommunications Union; g) Meets the needs of number users in Timor-Leste; and h) Takes into account number portability pursuant to the following article. 3. Service providers shall only use the numbers assigned to them by the Authority. 4. Save in duly justified exceptional circumstances, the Authority shall grant numbering requests made in accordance with the national numbering plan within 60 days from receiving the request. 5. Without prejudice to paragraph 4 of article 19, the Authority may, by written notice, require a service provider to vacate or migrate any numbers to facilitate the introduction of new telecommunications services or to accommodate new telecommunications service providers. 6. Where a service provider is required by the Authority to introduce, vacate or migrate any numbers that have been assigned to it, the Authority shall allow such service provider a reasonable period of time to do so taking into account the existing usage of numbers and the technical requirements, which shall, save in duly justified exceptional circumstances, be no less than three months after the written notice. Section 68 Mobile number portability 1. Subject to paragraph 3 of this article, the Authority shall establish procedures, rules and guidelines for the implementation of mobile number portability following an 18 month period from the date of entry into force of the present Decree-law. 2. Prior to implementing mobile number portability under the preceding paragraph, the Authority shall consult with the service providers in question according to paragraph 4 of article 19, and consider in particular: a) The costs of mobile number portability and their fair distribution among service providers and subscribers; b) The availability of technology permitting mobile number portability;