EXHIBIT 99.1

                                  CERTIFICATION

                         PURSUANT TO SECTION 906 OF THE
             SARBANES-OXLEY ACT OF 2002 (SUBSECTIONS (A) AND (B) OF
               SECTION 1350, CHAPTER 63 OF TITLE 18, UNITED STATES
                                      CODE)

     Pursuant to section 906 of the  Sarbanes-Oxley Act of 2002 (subsections (a)
and (b) of section 1350,  chapter 63 of title 18,  United States Code),  each of
the  undersigned  officers of  deltathree,  Inc.,  a Delaware  corporation  (the
"Company"), does hereby certify, to such officer's knowledge, that:

     The Quarterly  Report on Form 10-Q for the quarter ended June 30, 2003 (the
"Form 10-Q") of the Company  fully  complies  with the  requirements  of section
13(a) or 15(d) of the Securities Exchange Act of 1934, and information contained
in the Form 10-Q  fairly  presents,  in all  material  respects,  the  financial
condition and results of operations of the Company.


Dated:   AUGUST 7, 2003        /s/ SHIMMY ZIMELS
                               ------------------------------------------
                               Shimmy Zimels
                               Chief Executive Officer
                               (Principal Executive Officer)


Dated:   AUGUST 7, 2003        /s/ PAUL C. WHITE
                               -------------------------------------------
                               Paul C. White
                               Chief Financial Officer
                               (Principal Financial and Accounting Officer)



     This  certification  accompanies  this  Report  pursuant  to ss. 906 of the
Sarbanes-Oxley  Act of 2002 and shall not,  except to the extent required by the
Sarbanes-Oxley  Act of 2002,  be deemed filed by the Company for purposes of ss.
18 of the Securities Exchange AcT of 1934, as amended.



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