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        <link:definition>9955513 - Disclosure - ACCOUNTS RECEIVABLE, NET (Tables)</link:definition>
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        <link:definition>9955514 - Disclosure - INVENTORIES, NET (Tables)</link:definition>
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        <link:definition>9955516 - Disclosure - INTANGIBLE ASSETS, NET (Tables)</link:definition>
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        <link:definition>9955518 - Disclosure - STOCK-BASED COMPENSATION (Tables)</link:definition>
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        <link:definition>9955521 - Disclosure - SEGMENT INFORMATION (Tables)</link:definition>
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        <link:definition>9955522 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION (Tables)</link:definition>
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        <link:definition>9955524 - Disclosure - REVENUE RECOGNITION - Narrative (Details)</link:definition>
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        <link:definition>9955525 - Disclosure - REVENUE RECOGNITION - Schedule of Revenue by Customer Type (Details)</link:definition>
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        <link:definition>9955526 - Disclosure - REVENUE RECOGNITION - Schedule of Contract with Customer, Contract Asset, Contract Liability, and Receivable (Details)</link:definition>
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        <link:definition>9955527 - Disclosure - ACCOUNTS RECEIVABLE, NET - Schedule of Accounts, Notes, Loans and Financing Receivable (Details)</link:definition>
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        <link:definition>9955528 - Disclosure - ACCOUNTS RECEIVABLE, NET - Narrative (Details)</link:definition>
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        <link:definition>9955529 - Disclosure - INVENTORIES, NET (Details)</link:definition>
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        <link:definition>9955530 - Disclosure - PROPERTY AND EQUIPMENT, NET - Property, Plant and Equipment (Details)</link:definition>
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        <link:definition>9955531 - Disclosure - GOODWILL (Details)</link:definition>
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        <link:definition>9955532 - Disclosure - INTANGIBLE ASSETS, NET - Schedule of Finite-Lived Intangible Assets (Details)</link:definition>
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        <link:definition>9955532 - Disclosure - INTANGIBLE ASSETS, NET - Schedule of Finite-Lived Intangible Assets (Details)</link:definition>
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        <link:definition>9955533 - Disclosure - INTANGIBLE ASSETS, NET - Schedule of Amortization Expense (Details)</link:definition>
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        <link:definition>9955534 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Schedule of Other Assets (Details)</link:definition>
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      <link:roleType id="SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails" roleURI="http://telos.com/role/SEGMENTINFORMATIONScheduleofSegmentReportingInformationbySegmentDetails">
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      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONScheduleofSupplementalCashFlowInformationDetails" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONScheduleofSupplementalCashFlowInformationDetails">
        <link:definition>9955548 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION - Schedule of Supplemental Cash Flow Information (Details)</link:definition>
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  <xs:element id="tls_RevenueTimingOfTransferOfGoodsOrServiceMember" abstract="true" name="RevenueTimingOfTransferOfGoodsOrServiceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
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  <xs:element id="tls_StateLocalAndCommercialMember" abstract="true" name="StateLocalAndCommercialMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_USDepartmentOfDefenseMember" abstract="true" name="USDepartmentOfDefenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_U.S.DepartmentOfHomelandSecurityMember" abstract="true" name="U.S.DepartmentOfHomelandSecurityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
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  <xs:element id="tls_SecuritySolutionsSegmentMember" abstract="true" name="SecuritySolutionsSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_SecureNetworksSegmentMember" abstract="true" name="SecureNetworksSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_BillContractsReceivableNetOfAllowance" abstract="false" name="BillContractsReceivableNetOfAllowance" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="tls_IntangibleAssetsAmortizationExpense" abstract="false" name="IntangibleAssetsAmortizationExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
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  <xs:element id="tls_OtherCurrentLiabilitiesOther" abstract="false" name="OtherCurrentLiabilitiesOther" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_CreditAgreementMember" abstract="true" name="CreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_AlternativeBaseRateMember" abstract="true" name="AlternativeBaseRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_AdjustedDailySimpleSecuredOvernightFinancingRateSOFRMember" abstract="true" name="AdjustedDailySimpleSecuredOvernightFinancingRateSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_AdjustedTermSecuredOvernightFinancingRateSOFRMember" abstract="true" name="AdjustedTermSecuredOvernightFinancingRateSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" abstract="false" name="LineOfCreditFacilityAccordionFeatureHigherBorrowingCapacityOption" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_DebtInstrumentNumberOfVariableRates" abstract="false" name="DebtInstrumentNumberOfVariableRates" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="tls_DebtInstrumentIncrementalIncreaseInInterestRateDueToDefault" abstract="false" name="DebtInstrumentIncrementalIncreaseInInterestRateDueToDefault" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="tls_DebtInstrumentPriorNoticePeriod" abstract="false" name="DebtInstrumentPriorNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="tls_DebtInstrumentCovenantSeniorLeverageRatioMaximum" abstract="false" name="DebtInstrumentCovenantSeniorLeverageRatioMaximum" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="tls_ReceivablesExcludedFromCollateral" abstract="false" name="ReceivablesExcludedFromCollateral" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_Two016OmnibusLongTermIncentivePlanMember" abstract="true" name="Two016OmnibusLongTermIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardModifications" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardModifications" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
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  <xs:element id="tls_IssuanceOfCommonStockFor401KMatch" abstract="false" name="IssuanceOfCommonStockFor401KMatch" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_PurchaseOfInvestmentInAccountsPayableAndOtherAccruedLiabilities" abstract="false" name="PurchaseOfInvestmentInAccountsPayableAndOtherAccruedLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
