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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-03-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001168329</rptOwnerCik>
            <rptOwnerName>SEIFERT THOMAS G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10940 S PARKER ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 201</rptOwnerStreet2>
            <rptOwnerCity>PARKER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80134</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Financial Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK, $.00001 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2010-03-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.046</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1535225</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>SEE FOOTNOTE</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to a plan in accordance with Rule 10b5-1 under the Securities Exchange Act of 1934.</footnote>
        <footnote id="F2">Includes (i) 1,335,225 shares of common stock owned by Rocky Mtn. Advisors Corp of which Mr. Seifert is an officer, director and controlling shareholder and (ii) 200,000 share of common stock owned by a child of Mr. Seifert under the age of 18 and which Mr. Seifert is deemed to have dispositive and investment control over.</footnote>
        <footnote id="F3">such securities are held by Rocky Mtn. Advisors Corp.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Thomas Seifert</signatureName>
        <signatureDate>2010-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
