Electronic and Postal Communications (Competition) G.N. No. 420 (contd) relevant communications markets the relevant communication market. (2) In determining the relevant communications markets, the Authority shall take into account the following(a) the products or services that make up a specific market, as well as the geographic scope of that market; (b) the demand side substitutability, in order to measure the extent to which consumers are prepared or able to substitute other products or services for the products or services supplied by the licensee in question; and (c) the supply side substitutability, to determine the extent to which suppliers, other than the licensee in question, are able to supply products or services that provide a competitive alternative to consumers. PART VI GENERAL PROVISIONS Abuse of dominant position 16.-(1) Where the conduct of a dominant licensee has or may have the effect of substantially lessening competition in one or more communication markets, the Authority shall(a) require the dominant licensee to desist, change its conduct or adopt a particular conduct; or (b) implement appropriate remedies. (2) The Authority shall, before taking an action referred to under sub-regulation (1)(b), request the dominant licensee to refrain from the conduct that is inconsistent with these Regulations. Arbitration of disputes   17.-(1) Where a dispute arises between parties on issues having effect to substantially lessening competition, the aggrieved party may petition to the Authority to arbitrate and the respondent shall be served with a copy of the petition together with a written notice of hearing. (2) The aggrieved party shall submit his petition to the 79