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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-02-25</periodOfReport>

    <issuer>
        <issuerCik>0001103184</issuerCik>
        <issuerName>ULTICOM INC</issuerName>
        <issuerTradingSymbol>ULCM.PK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001293581</rptOwnerCik>
            <rptOwnerName>Chill Michael J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ULTICOM, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1020 BRIGGS ROAD</rptOwnerStreet2>
            <rptOwnerCity>MT. LAUREL</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>08054</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Stock Awards (units)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-02-25</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3105.5901</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>3105.5901</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3105.5901</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each Unit of the Deferred Stock Award settles automatically into one share of Ulticom Common Stock upon the Settlement Date (as defined below).</footnote>
        <footnote id="F2">The Deferred Stock Award settles on the earlier of (a) the date on which a Change in Control occurs (to the extent that such Change in Control also constitutes a change in ownership or effective control within the meaning of Section 409A(a)(2)(A)(v) of the Code and (b) January 2, 2012 (the &quot;Settlement Date&quot;).  The Deferred Stock Award shall vest 25% in each of the fiscal quarters ending April 30, 2010, July 31, 2010, October 31, 2010 and January 31, 2011 as a result of services provided during fiscal year 2010.  The Deferred Stock Award shall become 100% vested on January 31, 2011, subject to the continued service as a director with Ulticom, Inc. or upon a change in control.</footnote>
        <footnote id="F3">The Deferred Stock Award was issued in connection with service as a director during fiscal year 2010.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Dawn Branin, as Attorney in Fact for Michael Chill</signatureName>
        <signatureDate>2010-03-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
