content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001777827</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001005757</issuerCik>
        <issuerName>CSG SYSTEMS INTERNATIONAL INC</issuerName>
        <secFileNumber>000-27512</secFileNumber>
        <issuerAddress>
          <com:street1>169 INVERNESS DR W</com:street1>
          <com:street2>SUITE 300</com:street2>
          <com:city>ENGLEWOOD</com:city>
          <com:stateOrCountry>CO</com:stateOrCountry>
          <com:zipCode>80112</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>3037962850</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Schaaf David Neil</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Former Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Fidelity Brokerage Services LLC</name>
          <address>
            <com:street1>900 Salem Street</com:street1>
            <com:city>Smithfield</com:city>
            <com:stateOrCountry>RI</com:stateOrCountry>
            <com:zipCode>02917</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>500</noOfUnitsSold>
        <aggregateMarketValue>27185.05</aggregateMarketValue>
        <noOfUnitsOutstanding>29443284</noOfUnitsOutstanding>
        <approxSaleDate>02/29/2024</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>03/21/2020</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>79</amountOfSecuritiesAcquired>
        <paymentDate>03/21/2020</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>04/10/2020</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>200</amountOfSecuritiesAcquired>
        <paymentDate>04/10/2020</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>02/19/2021</acquiredDate>
        <natureOfAcquisitionTransaction>Restricted Stock Vesting</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>221</amountOfSecuritiesAcquired>
        <paymentDate>02/19/2021</paymentDate>
        <natureOfPayment>Compensation</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>Y</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>02/29/2024</noticeDate>
        <signature>/s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for David Schaaf</signature>
      </noticeSignature>
    </formData>
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text: 144
  0001777827
  XXXXXXXX
  LIVE
  0001005757
  CSG SYSTEMS INTERNATIONAL INC
  000-27512
  169 INVERNESS DR W
  SUITE 300
  ENGLEWOOD
  CO
  80112
  3037962850
  Schaaf David Neil
  Former Officer
  Common
  Fidelity Brokerage Services LLC
  900 Salem Street
  Smithfield
  RI
  02917
  500
  27185.05
  29443284
  02/29/2024
  NASDAQ
  Common
  03/21/2020
  Restricted Stock Vesting
  Issuer
  N
  79
  03/21/2020
  Compensation
  Common
  04/10/2020
  Restricted Stock Vesting
  Issuer
  N
  200
  04/10/2020
  Compensation
  Common
  02/19/2021
  Restricted Stock Vesting
  Issuer
  N
  221
  02/19/2021
  Compensation
  Y
  02/29/2024
  /s/ Gerardo Ibarra-Munoz, as a duly authorized representative of Fidelity Brokerage Services LLC, as attorney-in-fact for David Schaaf