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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

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

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000919742</issuerCik>
        <issuerName>Sanswire Corp.</issuerName>
        <issuerTradingSymbol>SNSR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001503279</rptOwnerCik>
            <rptOwnerName>Johnson Barbara M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>STATE ROAD 405</rptOwnerStreet1>
            <rptOwnerStreet2>BLDG M6-306A RM 1400</rptOwnerStreet2>
            <rptOwnerCity>KENNEDY SPACE CENTER</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>32815</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK OPTIONS</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.075</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>750000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.075</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2011-03-02</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-03-02</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK $.00001 par value</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>750000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2050000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Awarded fully-vested 3-year options as bonus for the year ended December 31, 2010.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Barbara M. Johnson</signatureName>
        <signatureDate>2011-03-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
