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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-11-27</periodOfReport>

    <issuer>
        <issuerCik>0000732713</issuerCik>
        <issuerName>BELLSOUTH CORP</issuerName>
        <issuerTradingSymbol>BLS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183698</rptOwnerCik>
            <rptOwnerName>STAVROPOULOS WILLIAM S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2030 WILLIAM H. DOW CENTER</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MIDLAND</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48674</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Deferral Shares</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-11-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>20.9181</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>43.025</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2010-01-01</value>
            </exerciseDate>
            <expirationDate>
                <value>2010-01-01</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20.9181</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25537.0697</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">SHARES OF PHANTOM STOCK CONVERT TO COMMON STOCK ON A ONE-FOR-ONE BASIS.</footnote>
        <footnote id="F2">SHARES OF PHANTOM STOCK ACQUIRED PURSUANT TO BELLSOUTH CORPORATION DEFERRAL PLAN IN TRANSACTIONS EXEMPT UNDER RULE 16b-3(d).</footnote>
        <footnote id="F3">THE REPORTING PERSON'S FORM 4 FILED ON NOVEMBER 2, 2006 REPORTED AN INCORRECT NUMBER OF SHARES IN SECTION 7.  THIS REPORT REFLECTS THE CORRECT TOTAL OF DERIVATIVE SECURITIES BENEFICIALLY OWNED FOLLOWING THE REPORTED TRANSACTION.</footnote>
        <footnote id="F4">INCLUDES SHARES OF PHANTOM STOCK ACQUIRED AS A RESULT OF REINVESTMENT OF DIVIDENDS ACCRUED ON PHANTOM SHARES PREVIOUSLY ACQUIRED UNDER VARIOUS DEFERRAL PLANS IN TRANSACTIONS EXEMPT UNDER RULE 16b-3 AND DEFERRED INTO PHANTOM ACCOUNT.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Marcy A. Bass, Attorney in Fact</signatureName>
        <signatureDate>2006-11-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2006-11-27
0000732713
BELLSOUTH CORP
BLS
0001183698
STAVROPOULOS WILLIAM S
2030 WILLIAM H. DOW CENTER
MIDLAND
MI
48674
1
0
0
0
Phantom Deferral Shares
2006-11-27
4
A
0
20.9181
43.025
A
2010-01-01
2010-01-01
Common Stock
20.9181
25537.0697
D
SHARES OF PHANTOM STOCK CONVERT TO COMMON STOCK ON A ONE-FOR-ONE BASIS.
SHARES OF PHANTOM STOCK ACQUIRED PURSUANT TO BELLSOUTH CORPORATION DEFERRAL PLAN IN TRANSACTIONS EXEMPT UNDER RULE 16b-3(d).
THE REPORTING PERSON'S FORM 4 FILED ON NOVEMBER 2, 2006 REPORTED AN INCORRECT NUMBER OF SHARES IN SECTION 7.  THIS REPORT REFLECTS THE CORRECT TOTAL OF DERIVATIVE SECURITIES BENEFICIALLY OWNED FOLLOWING THE REPORTED TRANSACTION.
INCLUDES SHARES OF PHANTOM STOCK ACQUIRED AS A RESULT OF REINVESTMENT OF DIVIDENDS ACCRUED ON PHANTOM SHARES PREVIOUSLY ACQUIRED UNDER VARIOUS DEFERRAL PLANS IN TRANSACTIONS EXEMPT UNDER RULE 16b-3 AND DEFERRED INTO PHANTOM ACCOUNT.
Marcy A. Bass, Attorney in Fact
2006-11-29