Exhibit 99.1

                  Certification of CEO and CFO Pursuant to
                          18 U.S.C. Section 1350,
                           As Adopted Pursuant to
               Section 906 of the Sarbanes-Oxley Act of 2002

In connection with the Quarterly Report on Form 10-Q of deltathree, Inc.
(the "Company") for the quarterly period ended June 30, 2002 as filed with
the Securities and Exchange Commission on the date hereof (the "Report"),
Shimmy Zimels, as Chief Executive Officer of the Company, and Paul C.
White, as Chief Financial Officer of the Company, each hereby certifies,
pursuant to 18 U.S.C. ss. 1350, as adopted pursuant to ss. 906 of the
Sarbanes-Oxley Act of 2002, that, to the best of his knowledge:

         (1) The Report fully complies with the requirements of Section
13(a) or 15(d) of the Securities Exchange Act of 1934; and

         (2) The information contained in the Report fairly presents, in
all material respects, the financial condition and result of operations of
the Company.


/s/ Shimmy Zimels
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Shimmy Zimels
Chief Executive Officer
August 14, 2002


/s/ Paul C. White
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Paul C. White
Chief Financial Officer
August 14, 2002



This certification accompanies the 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.