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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001349360-08-000003.txt : 20080512
<SEC-HEADER>0001349360-08-000003.hdr.sgml : 20080512
<ACCEPTANCE-DATETIME>20080512171823
ACCESSION NUMBER:		0001349360-08-000003
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080512
FILED AS OF DATE:		20080512
DATE AS OF CHANGE:		20080512

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			INTERPHASE CORP
		CENTRAL INDEX KEY:			0000728249
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER COMMUNICATIONS EQUIPMENT [3576]
		IRS NUMBER:				751549797
		STATE OF INCORPORATION:			TX
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		13800 SENLAC DR
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75234
		BUSINESS PHONE:		2146545000

	MAIL ADDRESS:	
		STREET 1:		13800 SENLAC DR
		STREET 2:		13800 SENLAC DR
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75234

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			TIPTON THOMAS N JR
		CENTRAL INDEX KEY:			0001349360

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-13071
		FILM NUMBER:		08824774

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		214-654-5000

	MAIL ADDRESS:	
		STREET 1:		2901 NORTH DALLAS PARKWAY
		STREET 2:		SUITE 200
		CITY:			PLANO
		STATE:			TX
		ZIP:			75093
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000728249</issuerCik>
        <issuerName>INTERPHASE CORP</issuerName>
        <issuerTradingSymbol>INPH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001349360</rptOwnerCik>
            <rptOwnerName>TIPTON THOMAS N JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2901 NORTH DALLAS PARKWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PLANO</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75093</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CFO &amp; VP of Finance</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-05-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>230</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.61</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>36153</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Automatic sale made pursuant to a previously adopted Rule 10b5-1 Trading Plan entered into as of September 13, 2007.  The sale represents only enough shares to cover the estimated tax withholding obligation for the vesting of restricted stock.  The Reporting Person is holding the remaining shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Thomas N Tipton Jr</signatureName>
        <signatureDate>2008-05-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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