EXHIBIT 15.3 CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM MER Telemanagement Solutions Ltd. We hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Files No. 333-12014 and No. 333-123321) and Form F-3 (File No. 333-128225) of Mer Telemanagement Solutions Ltd., of our report dated January 18, 2008 relating to the financial statements of TABS Brazil Comercio e Servicos de Software Ltda. as of December 31, 2007 and 2006 ,which reports appear in this Annual Report on Form 20-F of Mer Telemanagement Solutions Ltd. for the year ended December 31, 2008. /S/ BDO TREVISAN AUDITORES INDEPENDENTES BDO TREVISAN AUDITORES INDEPENDENTES Sao Paulo - SP - Brazil Sao Paulo - Brazil, March 28, 2009