<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:00bd4ea9-b55e-4211-a669-19b7fc8d50fc,g:fe23032f-1b34-4d76-94d1-6ee997d5fb55-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:tls="http://telos.com/20240930" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://telos.com/20240930">
  <xs:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20240930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20240930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20240930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="tls-20240930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://telos.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFOPERATIONS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFOPERATIONS">
        <link:definition>9952151 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVELOSS">
        <link:definition>9952152 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETS" roleURI="http://telos.com/role/CONSOLIDATEDBALANCESHEETS">
        <link:definition>9952153 - Statement - CONSOLIDATED BALANCE SHEETS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDBALANCESHEETSParenthetical" roleURI="http://telos.com/role/CONSOLIDATEDBALANCESHEETSParenthetical">
        <link:definition>9952154 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCASHFLOWS" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS">
        <link:definition>9952155 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY" roleURI="http://telos.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY">
        <link:definition>9952156 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ORGANIZATION" roleURI="http://telos.com/role/ORGANIZATION">
        <link:definition>9952157 - Disclosure - ORGANIZATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIES" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIES">
        <link:definition>9952158 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITION" roleURI="http://telos.com/role/REVENUERECOGNITION">
        <link:definition>9952159 - Disclosure - REVENUE RECOGNITION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENET" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENET">
        <link:definition>9952160 - Disclosure - ACCOUNTS RECEIVABLE, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNET" roleURI="http://telos.com/role/INVENTORIESNET">
        <link:definition>9952161 - Disclosure - INVENTORIES, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNET" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNET">
        <link:definition>9952162 - Disclosure - PROPERTY AND EQUIPMENT, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GOODWILL" roleURI="http://telos.com/role/GOODWILL">
        <link:definition>9952163 - Disclosure - GOODWILL</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNET" roleURI="http://telos.com/role/INTANGIBLEASSETSNET">
        <link:definition>9952164 - Disclosure - INTANGIBLE ASSETS, NET</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTS" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTS">
        <link:definition>9952165 - Disclosure - OTHER BALANCE SHEET COMPONENTS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONS" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONS">
        <link:definition>9952166 - Disclosure - DEBT AND OTHER OBLIGATIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATION" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATION">
        <link:definition>9952167 - Disclosure - STOCK-BASED COMPENSATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SHAREREPURCHASES" roleURI="http://telos.com/role/SHAREREPURCHASES">
        <link:definition>9952168 - Disclosure - SHARE REPURCHASES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSS" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSS">
        <link:definition>9952169 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHARE" roleURI="http://telos.com/role/LOSSPERSHARE">
        <link:definition>9952170 - Disclosure - LOSS PER SHARE</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RELATEDPARTYTRANSACTIONS" roleURI="http://telos.com/role/RELATEDPARTYTRANSACTIONS">
        <link:definition>9952171 - Disclosure - RELATED PARTY TRANSACTIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATION" roleURI="http://telos.com/role/SEGMENTINFORMATION">
        <link:definition>9952172 - Disclosure - SEGMENT INFORMATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="COMMITMENTSANDCONTINGENCIES" roleURI="http://telos.com/role/COMMITMENTSANDCONTINGENCIES">
        <link:definition>9952173 - Disclosure - COMMITMENTS AND CONTINGENCIES</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATION" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATION">
        <link:definition>9952174 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESPolicies" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESPolicies">
        <link:definition>9954471 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESTables" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESTables">
        <link:definition>9954472 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONTables" roleURI="http://telos.com/role/REVENUERECOGNITIONTables">
        <link:definition>9954473 - Disclosure - REVENUE RECOGNITION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETTables" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETTables">
        <link:definition>9954474 - Disclosure - ACCOUNTS RECEIVABLE, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNETTables" roleURI="http://telos.com/role/INVENTORIESNETTables">
        <link:definition>9954475 - Disclosure - INVENTORIES, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNETTables" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNETTables">
        <link:definition>9954476 - Disclosure - PROPERTY AND EQUIPMENT, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETTables" roleURI="http://telos.com/role/INTANGIBLEASSETSNETTables">
        <link:definition>9954477 - Disclosure - INTANGIBLE ASSETS, NET (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSTables" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSTables">
        <link:definition>9954478 - Disclosure - OTHER BALANCE SHEET COMPONENTS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONTables" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONTables">
        <link:definition>9954479 - Disclosure - STOCK-BASED COMPENSATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSSTables" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSSTables">
        <link:definition>9954480 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHARETables" roleURI="http://telos.com/role/LOSSPERSHARETables">
        <link:definition>9954481 - Disclosure - LOSS PER SHARE (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONTables" roleURI="http://telos.com/role/SEGMENTINFORMATIONTables">
        <link:definition>9954482 - Disclosure - SEGMENT INFORMATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONTables" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONTables">
        <link:definition>9954483 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ORGANIZATIONDetails" roleURI="http://telos.com/role/ORGANIZATIONDetails">
        <link:definition>9954484 - Disclosure - ORGANIZATION (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails">
        <link:definition>9954485 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESRestructuringExpensesandImpairmentLossDetails" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESRestructuringExpensesandImpairmentLossDetails">
        <link:definition>9954486 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Restructuring Expenses and Impairment Loss (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SIGNIFICANTACCOUNTINGPOLICIESChangesinRestructuringExpensesAccrualDetails" roleURI="http://telos.com/role/SIGNIFICANTACCOUNTINGPOLICIESChangesinRestructuringExpensesAccrualDetails">
        <link:definition>9954487 - Disclosure - SIGNIFICANT ACCOUNTING POLICIES - Changes in Restructuring Expenses Accrual (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONNarrativeDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONNarrativeDetails">
        <link:definition>9954488 - Disclosure - REVENUE RECOGNITION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONNarrativeDetails_1" roleURI="http://telos.com/role/REVENUERECOGNITIONNarrativeDetails_1">
        <link:definition>9954488 - Disclosure - REVENUE RECOGNITION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONDisaggregationofRevenueDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONDisaggregationofRevenueDetails">
        <link:definition>9954489 - Disclosure - REVENUE RECOGNITION - Disaggregation of Revenue (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="REVENUERECOGNITIONScheduleofContractBalancesDetails" roleURI="http://telos.com/role/REVENUERECOGNITIONScheduleofContractBalancesDetails">
        <link:definition>9954490 - Disclosure - REVENUE RECOGNITION - Schedule of Contract Balances (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETScheduleofAccountsNotesLoansandFinancingReceivableDetails" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETScheduleofAccountsNotesLoansandFinancingReceivableDetails">
        <link:definition>9954491 - Disclosure - ACCOUNTS RECEIVABLE, NET - Schedule of Accounts, Notes, Loans and Financing Receivable (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCOUNTSRECEIVABLENETNarrativeDetails" roleURI="http://telos.com/role/ACCOUNTSRECEIVABLENETNarrativeDetails">
        <link:definition>9954492 - Disclosure - ACCOUNTS RECEIVABLE, NET - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INVENTORIESNETDetails" roleURI="http://telos.com/role/INVENTORIESNETDetails">
        <link:definition>9954493 - Disclosure - INVENTORIES, NET (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="PROPERTYANDEQUIPMENTNETDetails" roleURI="http://telos.com/role/PROPERTYANDEQUIPMENTNETDetails">
        <link:definition>9954494 - Disclosure - PROPERTY AND EQUIPMENT, NET (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GOODWILLDetails" roleURI="http://telos.com/role/GOODWILLDetails">
        <link:definition>9954495 - Disclosure - GOODWILL (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETFiniteLivedIntangibleAssetsDetails" roleURI="http://telos.com/role/INTANGIBLEASSETSNETFiniteLivedIntangibleAssetsDetails">
        <link:definition>9954496 - Disclosure - INTANGIBLE ASSETS, NET - Finite-Lived Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETFiniteLivedIntangibleAssetsDetails_1" roleURI="http://telos.com/role/INTANGIBLEASSETSNETFiniteLivedIntangibleAssetsDetails_1">
        <link:definition>9954496 - Disclosure - INTANGIBLE ASSETS, NET - Finite-Lived Intangible Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETNarrativeDetails" roleURI="http://telos.com/role/INTANGIBLEASSETSNETNarrativeDetails">
        <link:definition>9954497 - Disclosure - INTANGIBLE ASSETS, NET - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="INTANGIBLEASSETSNETAmortizationExpenseDetails" roleURI="http://telos.com/role/INTANGIBLEASSETSNETAmortizationExpenseDetails">
        <link:definition>9954498 - Disclosure - INTANGIBLE ASSETS, NET - Amortization Expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSOtherAssetsDetails" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSOtherAssetsDetails">
        <link:definition>9954499 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Other Assets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSAccountsPayableandOtherAccruedLiabilitiesDetails" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSAccountsPayableandOtherAccruedLiabilitiesDetails">
        <link:definition>9954500 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Accounts Payable and Other Accrued Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="OTHERBALANCESHEETCOMPONENTSOtherCurrentLiabilitiesDetails" roleURI="http://telos.com/role/OTHERBALANCESHEETCOMPONENTSOtherCurrentLiabilitiesDetails">
        <link:definition>9954501 - Disclosure - OTHER BALANCE SHEET COMPONENTS - Other Current Liabilities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONSRevolvingCreditFacilityDetails" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONSRevolvingCreditFacilityDetails">
        <link:definition>9954502 - Disclosure - DEBT AND OTHER OBLIGATIONS - Revolving Credit Facility (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="DEBTANDOTHEROBLIGATIONSOtherFinancingObligationsDetails" roleURI="http://telos.com/role/DEBTANDOTHEROBLIGATIONSOtherFinancingObligationsDetails">
        <link:definition>9954503 - Disclosure - DEBT AND OTHER OBLIGATIONS - Other Financing Obligations (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONNarrativeDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONNarrativeDetails">
        <link:definition>9954504 - Disclosure - STOCK-BASED COMPENSATION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONStockBasedCompensationExpenseIncurredDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONStockBasedCompensationExpenseIncurredDetails">
        <link:definition>9954505 - Disclosure - STOCK-BASED COMPENSATION - Stock-Based Compensation Expense Incurred (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONNonvestedRestrictedStockUnitsActivityDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONNonvestedRestrictedStockUnitsActivityDetails">
        <link:definition>9954506 - Disclosure - STOCK-BASED COMPENSATION - Nonvested Restricted Stock Units Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="STOCKBASEDCOMPENSATIONStockOptionActivityDetails" roleURI="http://telos.com/role/STOCKBASEDCOMPENSATIONStockOptionActivityDetails">
        <link:definition>9954507 - Disclosure - STOCK-BASED COMPENSATION - Stock Option Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SHAREREPURCHASESDetails" roleURI="http://telos.com/role/SHAREREPURCHASESDetails">
        <link:definition>9954508 - Disclosure - SHARE REPURCHASES (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ACCUMULATEDOTHERCOMPREHENSIVELOSSDetails" roleURI="http://telos.com/role/ACCUMULATEDOTHERCOMPREHENSIVELOSSDetails">
        <link:definition>9954509 - Disclosure - ACCUMULATED OTHER COMPREHENSIVE LOSS (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="LOSSPERSHAREDetails" roleURI="http://telos.com/role/LOSSPERSHAREDetails">
        <link:definition>9954510 - Disclosure - LOSS PER SHARE (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RELATEDPARTYTRANSACTIONSDetails" roleURI="http://telos.com/role/RELATEDPARTYTRANSACTIONSDetails">
        <link:definition>9954511 - Disclosure - RELATED PARTY TRANSACTIONS (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONNarrativeDetails" roleURI="http://telos.com/role/SEGMENTINFORMATIONNarrativeDetails">
        <link:definition>9954512 - Disclosure - SEGMENT INFORMATION - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SEGMENTINFORMATIONOperationsbyBusinessSegmentDetails" roleURI="http://telos.com/role/SEGMENTINFORMATIONOperationsbyBusinessSegmentDetails">
        <link:definition>9954513 - Disclosure - SEGMENT INFORMATION - Operations by Business Segment (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONCashCashEquivalentsandRestrictedCashDetails" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONCashCashEquivalentsandRestrictedCashDetails">
        <link:definition>9954514 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION - Cash, Cash Equivalents, and Restricted Cash (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SUPPLEMENTALCASHFLOWINFORMATIONSupplementalCashFlowInformationDetails" roleURI="http://telos.com/role/SUPPLEMENTALCASHFLOWINFORMATIONSupplementalCashFlowInformationDetails">
        <link:definition>9954515 - Disclosure - SUPPLEMENTAL CASH FLOW INFORMATION - Supplemental Cash Flow Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="tls_CostOfGoodsAndServiceExcludingImpairmentsDepreciationDepletionAndAmortization" abstract="false" name="CostOfGoodsAndServiceExcludingImpairmentsDepreciationDepletionAndAmortization" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_PaymentOfDFTHoldbackAmount" abstract="false" name="PaymentOfDFTHoldbackAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_TelosIdMember" abstract="true" name="TelosIdMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_A2022RestructuringPlanMember" abstract="true" name="A2022RestructuringPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_A2024RestructuringPlanMember" abstract="true" name="A2024RestructuringPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ResearchAndDevelopmentSellingGeneralAndAdministrativeExpensesMember" abstract="true" name="ResearchAndDevelopmentSellingGeneralAndAdministrativeExpensesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_A2022And2024RestructuringPlansMember" abstract="true" name="A2022And2024RestructuringPlansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_RevenueTimingOfTransferOfGoodsOrServiceMember" abstract="true" name="RevenueTimingOfTransferOfGoodsOrServiceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_FederalGovernmentMember" abstract="true" name="FederalGovernmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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.SDepartmentOfHomelandSecurityMember" abstract="true" name="U.SDepartmentOfHomelandSecurityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_CostPlusFixedFeeMember" abstract="true" name="CostPlusFixedFeeMember" 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"/>
  <xs:element id="tls_FurnitureAndEquipmentMember" abstract="true" name="FurnitureAndEquipmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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_InProcessSoftwareDevelopmentCostsMember" abstract="true" name="InProcessSoftwareDevelopmentCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ResearchAndDevelopmentNettingMember" abstract="true" name="ResearchAndDevelopmentNettingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_IntangibleAssetsAmortizationExpense" abstract="false" name="IntangibleAssetsAmortizationExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_OtherAccruedExpensesCurrent" abstract="false" name="OtherAccruedExpensesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <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_SoftwareLicensesUnderDeliveryOrderMember" abstract="true" name="SoftwareLicensesUnderDeliveryOrderMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_SoftwareLicenseDeliveryOrderNumberOfExercisableExtensionOptions" abstract="false" name="SoftwareLicenseDeliveryOrderNumberOfExercisableExtensionOptions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="tls_SoftwareLicenseDeliveryOrderPeriodOfExercisableExtensionOptions" abstract="false" name="SoftwareLicenseDeliveryOrderPeriodOfExercisableExtensionOptions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <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_CertainSeniorExecutivesAndEmployeesMember" abstract="true" name="CertainSeniorExecutivesAndEmployeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ShareBasedPaymentArrangementExpenseCumulativeCatchUpAdjustmentMember" abstract="true" name="ShareBasedPaymentArrangementExpenseCumulativeCatchUpAdjustmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="tls_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfCommonSharesThatMaybeSettledBasedOnConditions" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNumberOfCommonSharesThatMaybeSettledBasedOnConditions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="tls_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingConditionsStockPricesThresholdNumberOfConsecutiveDays" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingConditionsStockPricesThresholdNumberOfConsecutiveDays" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="tls_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstandingExercisableAndVestedOrExpectedToVest" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueOutstandingExercisableAndVestedOrExpectedToVest" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="tls_ServiceBasedRSUAwardsMember" abstract="true" name="ServiceBasedRSUAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="tls_IncrementalCommonSharesExcludedFromTheDilutiveEffect" abstract="false" name="IncrementalCommonSharesExcludedFromTheDilutiveEffect" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="tls_EmmettWoodMember" abstract="true" name="EmmettWoodMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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_IntangibleAssetsTransferredToExtinguishOtherFinancingObligations" abstract="false" name="IntangibleAssetsTransferredToExtinguishOtherFinancingObligations" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
