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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2004-01-30</periodOfReport>

    <dateOfOriginalSubmission>2004-02-02</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001001868</issuerCik>
        <issuerName>FIBERNET TELECOM GROUP INC\</issuerName>
        <issuerTradingSymbol>FTGX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000948046</rptOwnerCik>
            <rptOwnerName>DEUTSCHE BANK AG\</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>TAUNUSANLAGE 12 D-60325</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FRANKFURT AM MAIN</rptOwnerCity>
            <rptOwnerState>I8</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>GERMANY (WEST)</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common</value>
            </securityTitle>
            <transactionDate>
                <value>2004-01-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>184846</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.001</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4980619</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrants</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.001</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-01-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>X</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>184964</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.001</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-01-30</value>
            </exerciseDate>
            <expirationDate>
                <value>2007-11-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, Par Value $0.001 per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>184846</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>421747</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <remarks>This filing is made to amend the Form 4 filed by the Reporting Person on February 2, 2004, and to also amend the Form 4 filed by the Reporting Person on March 4, 2004, which second Form 4: (i) reported, in an amended fashion, the cashless exercise of warrants effected by the Reporting Person on January 30, 2004; and (ii) restated certain beneficial ownership information presented in previous Forms 4 filed by the Reporting Person on February 2, 2004, October 16, 2003, and September 10, 2003.  Certain of the restatements did not properly account for the 1-for-30 reverse stock and warrant split effected by the Issuer in May 2003.  This Amendment is intended to accurately restate as follows the beneficial ownership information in the Reporting Person's previous Form 4 filings (see Table I, Column 5; and Table II, Column 9 in each Form 4):  (i) Forms 4 filed on March 4, 2004, and February 2, 2004:  Non-Derivative Securities Beneficially Owned: 4,980,619 common shares,  Derivative Securities Beneficially Owned: 421,747 warrants;  (ii) Form 4 filed on October 16, 2003:  Non-Derivative Securities Beneficially Owned: 4,795,773 common shares,  Derivative Securities Beneficially Owned: 606,711 warrants; (iii) Form 4 filed on September 10, 2003:  Non-Derivative Securities Beneficially Owned: 4,615,069 common shares,  Derivative Securities Beneficially Owned: 791,005 warrants; and (iv) Form 4 filed on  February 24, 2003:  Non-Derivative Securities Beneficially Owned: 137,718,560 common shares,  Derivative Securities Beneficially Owned: 24,464,345 warrants.</remarks>

    <ownerSignature>
        <signatureName>Jeffrey A Ruiz</signatureName>
        <signatureDate>2004-05-17</signatureDate>
    </ownerSignature>
</ownershipDocument>

