<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-03-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001086740</issuerCik>
        <issuerName>DELTATHREE INC</issuerName>
        <issuerTradingSymbol>DDDC.PK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001456791</rptOwnerCik>
            <rptOwnerName>Stevanovski Robert</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>349-L COPPERFIELD BOULEVARD, #407</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CONCORD</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001456782</rptOwnerCik>
            <rptOwnerName>D4 Holdings, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>349-L COPPERFIELD BOULEVARD, #407</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CONCORD</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001456822</rptOwnerCik>
            <rptOwnerName>Manna Holdings, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>349-L COPPERFIELD BOULEVARD, #402</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CONCORD</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001456821</rptOwnerCik>
            <rptOwnerName>Praescient, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO BOX 1086</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CORNELIUS</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28031</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.096</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2011-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2011-03-02</value>
            </exerciseDate>
            <expirationDate>
                <value>2021-03-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, $0.001 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1000000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1000000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By D4 Holdings, LLC</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The reported securities are held directly by D4 Holdings, LLC (&quot;D4 Holdings&quot;). The securities are held indirectly by Manna Holdings, LLC (&quot;Manna Holdings&quot;), as sole member of D4 Holdings, and Praescient, LLC (&quot;Praescient&quot;), as the sole manager of D4 Holdings and managing member of Manna Holdings. Robert Stevanovski is the manager of Praescient.</footnote>
        <footnote id="F2">Robert Stevanovski is a principal of Manna Holdings and the manager of Praescient, which serves as the sole manager of D4 Holdings, and as the managing member of Manna Holdings. Manna Holdings is the sole member of D4 Holdings. As such, Mr. Stevanovski, Praescient and Manna Holdings may be deemed to beneficially own the securities reported herein and owned directly by D4 Holdings. Each of Mr. Stevanovski, Praescient and Manna Holdings disclaims beneficial ownership of such securities, and this report shall not be deemed an admission that such reporting person is the beneficial owner of the securities for the purpose of Section 16 or for any other purpose, except to the extent of such reporting person's pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Robert Stevanovski, by Colleen Jones, attorney-in-fact</signatureName>
        <signatureDate>2011-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ D4 Holdings, LLC by Praescient, its manager, by Colleen Jones, authorized signatory</signatureName>
        <signatureDate>2011-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Manna Holdings, LLC, by Praescient, its managing member, by Colleen Jones, authorized signatory</signatureName>
        <signatureDate>2011-03-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Praescient, LLC, by Colleen Jones, authorized signatory</signatureName>
        <signatureDate>2011-03-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
