No. 12 Tanzania Communications Regulatory Authority 2003 17 (a) the costs of making, producing and supplying the goods or services; (b) the desire to promote competitive rates and attract the market; (c) any relevant benchmarks including international benchmarks for prices, costs and return on assets in comparable industries; (d) the financial implications of the determination; (e) the consumer and investor interest; (f) the return on assets in the regulated sector; (g) any other factor specified in relevant sector legislation; (h) any other factors the Authority considers relevant. (3) The Authority shall publish in the Government Gazette all the rates tariffs and charges regulated by the Authority. Power to obtain inforination, documents and evidence 17. - (1) Where the Authority has reasons to believe that a person is capable of supplying information, producing a document or giving evidence that may assist in the performance of any of its functions, any officer of the Authority may, by summons signed by the a DirectorGeneral or Secretary of the Authority served on that person, require that person (a) to furnish the information in writing, signed by him, in the case of a body corporate, signed by a competent officer of the body corporate; (b) to produce the document to the Authority; (c) to appear before the Authority to give evidence (2) A summons under this section shall specify the required time and manner of compliance. (3) The Authority may require that any evidence referred to under this section be given on oath or affirmation, and in that case, the Director General, the Secretary or any officer of the Authority may administer the oath or affirmation. (4) Any person shall not be excused from complying with summons under this section on the grounds that compliance may tend to incriminate the person or make the person liable to a penalty, save that information, documents and evidence provided in answer to a summons will not be admissible in any proceedings against the person other than proceedings under this Act, sector legislation, the Fair Competition Act, 2003 or any environment protection legislation.