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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934
                               (Amendment No. 1)*


                         CSG Systems International Inc.
--------------------------------------------------------------------------------
                                (Name of Issuer)


                          Common Stock, par value $0.01
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                    126349109
--------------------------------------------------------------------------------
                                 (CUSIP Number)


                                December 31, 2004
--------------------------------------------------------------------------------
            (Date of Event Which Requires Filing of this Statement)


     Check the  appropriate  box to  designate  the rule  pursuant to which this
Schedule is filed:

          [_] Rule 13d-1(b)

          [X] Rule 13d-1(c)

          [_] Rule 13d-1(d)

----------
*    The  remainder  of this  cover  page  shall be filled  out for a  reporting
     person's  initial  filing on this form with respect to the subject class of
     securities,  and for any subsequent amendment containing  information which
     would alter the disclosures provided in a prior cover page.

     The  information  required in the remainder of this cover page shall not be
deemed to be "filed"  for the purpose of Section 18 of the  Securities  Exchange
Act of 1934 ("Act") or otherwise  subject to the  liabilities of that section of
the Act but shall be subject to all other  provisions of the Act  (however,  see
the Notes).



CUSIP No.    126349109
            ---------------------


1.   NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

      Ahmet H. Okumus

2.   

     CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE  INSTRUCTIONS) 
                                                                        (a) [_]
                                                                        (b) [X]

3.   SEC USE ONLY


4.   CITIZENSHIP OR PLACE OF ORGANIZATION

     Republic of Turkey

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.   SOLE VOTING POWER

     0

6.   SHARED VOTING POWER

     3,054,135

7.   SOLE DISPOSITIVE POWER

     0

8.   SHARED DISPOSITIVE POWER

     3,054,135

9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     3,054,135

10.  CHECK BOX IF THE AGGREGATE  AMOUNT IN ROW (9) EXCLUDES  CERTAIN SHARES (SEE
     INSTRUCTIONS)
                                                                         [_]

11.  PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     5.97%

12.  TYPE OF REPORTING PERSON (SEE INSTRUCTIONS)

     IN

--------------------------------------------------------------------------------


CUSIP No.    126349109
            ---------------------

Item 1(a).  Name of Issuer:

            CSG Systems International Inc.
            --------------------------------------------------------------------

      (b). Address of Issuer's Principal Executive Offices:

            7887 East Belleview Avenue
            Suite 1000
            Englewood, CO 80111
            --------------------------------------------------------------------

Item 2(a).  Names of Persons Filing:

            Ahmet H. Okumus
            --------------------------------------------------------------------

      (b).  Address of Principal Business Office, or if None, Residence:

            850 Third Avenue, 10th Floor
            New York, New York 10022
            --------------------------------------------------------------------

      (c).  Citizenship:

            Ahmet H. Okumus - Republic of Turkey
            --------------------------------------------------------------------

      (d).  Title of Class of Securities:

            Common Stock, par value $0.01 (the "Common Stock")
            --------------------------------------------------------------------

      (e).  CUSIP Number:

            126349109
            --------------------------------------------------------------------

Item 3.   If  This  Statement  is  filed  pursuant  to  ss.240.13d-1(b)  or
          240.13d-2(b), or (c), check whether the person filing is a:

     (a)  [_] Broker or dealer  registered under Section 15 of the Exchange Act
              (15 U.S.C. 78c).

     (b)  [_] Bank as defined in Section 3(a)(6) of the Exchange Act (15 U.S.C.
              78c).

     (c)  [_] Insurance  company as defined in Section 3(a)(19) of the Exchange
              Act (15 U.S.C. 78c).

     (d)  [_] Investment  company  registered under Section 8 of the Investment
              Company Act of 1940 (15 U.S.C. 80a-8).

     (e)  [_] An investment adviser in accordance with s.240.13d-1(b)(1)(ii)(E);

     (f)  [_] An employee  benefit plan or endowment  fund in  accordance  with
              s.240.13d-1(b)(1)(ii)(F);

     (g)  [_] A parent  holding  company or control  person in accordance  with
              Rule 13d-1(b)(1)(ii)(G);

     (h)  [_] A savings  association  as defined in Section 3(b) of the Federal
              Deposit Insurance Act (12 U.S.C.1813);

     (i)  [_] A  church  plan  that  is  excluded  from  the  definition  of an
              investment  company  under  Section  3(c)(14)  of the  Investment
              Company Act of 1940 (15 U.S.C. 80a-3);

     (j)  [_] Group, in accordance with s.240.13d-1(b)(1)(ii)(J).

Item 4.  Ownership.

     Provide  the  following  information  regarding  the  aggregate  number and
percentage of the class of securities of the issuer identified in Item 1.

     (a)  Amount beneficially owned:

          Ahmet H. Okumus - 3,054,135
          ----------------------------------------------------------------------

     (b)  Percent of class:

          Ahmet H. Okumus - 5.97%
          ----------------------------------------------------------------------

     (c)  Number of shares as to which the person has:

          Ahmet H. Okumus

          (i)   Sole power to vote or to direct the vote               0
                                                        -----------------------,


          (ii) Shared power to vote or to direct the vote        3,054,135
                                                          ---------------------,


          (iii) Sole power to dispose or to direct the                 0
                disposition of                            _____________________,


          (iv)  Shared power to dispose or to direct the       3,054,135
                disposition of                            _____________________.


Item 5.  Ownership of Five Percent or Less of a Class.

     If this  statement  is being  filed to report  the fact that as of the date
hereof the reporting  person has ceased to be the beneficial  owner of more than
five percent of the class of securities, check the following [ ].

            Not applicable.
          -------------------------------------------------------------------


Item 6.  Ownership of More Than Five Percent on Behalf of Another Person.

     If any other  person is known to have the right to  receive or the power to
direct the receipt of dividends  from,  or the  proceeds  from the sale of, such
securities,  a statement  to that effect  should be included in response to this
item and, if such interest relates to more than five percent of the class,  such
person  should be  identified.  A listing of the  shareholders  of an investment
company registered under the Investment Company Act of 1940 or the beneficiaries
of employee benefit plan, pension fund or endowment fund is not required.

          Ahmet H. Okumus  ("Okumus") with respect to the shares of Common Stock
          the Company are also beneficially  owned by (a) (i) Okumus Opportunity
          Fund, Ltd., (ii) Okumus Leveraged Opportunity Fund, Ltd., (iii) Okumus
          Technology  Value Fund,  Ltd., (iv) Okumus Market Neutral Fund,  Ltd.,
          and  (v)  Okumus  Diversified  Value  Fund,  Ltd.,  all of  which  are
          international  business  companies  incorporated in the British Virgin
          Islands,  for which Okumus Capital,  LLC, a Delaware limited liability
          company ("OC") of which Okumus is the managing  member,  serves as the
          investment manager;  (b) Okumus Opportunity  Partners,  LP, a Delaware
          limited  partnership,  for which  Okumus  Advisors,  LLC,  a  Delaware
          limited  liability  company of which  Okumus is the  managing  member,
          serves  as  general  partner  and  investment   advisor;   (c)  Okumus
          Technology  Value Partners,  LP, a Delaware limited  partnership,  for
          which Okumus  Technology  Advisors,  LLC, a Delaware limited liability
          company  of which  Okumus is the  managing  member,  serves as general
          partner and investment advisor (d) Okumus Market Neutral Partners, LP,
          a  Delaware  limited  partnership,  for which  Okumus  Market  Neutral
          Advisors, LLC, a Delaware limited liability company of which Okumus is
          the managing member, serves as general partner and investment advisor;
          and (e) Okumus  Diversified  Value Partners,  L.P., a Delaware limited
          partnership,  for which Okumus Diversified  Advisors,  LLC, a Delaware
          limited  liability  company of which  Okumus is the  managing  member,
          serves as general  partner and  investment  advisor.  In addition,  OC
          manages,  on  a  discretionary  basis,  a  separate  account  for  the
          unrelated   entities  of  Daiwa  Super  Hedge  Fund  Ltd.  and  dbX-US
          Long/Short Equity 5 Fund.

          The Reporting Person and all of the foregoing  entities  affirmatively
          disclaim  being a "group" for purposes of Section 16 of the Securities
          Exchange Act of 1934, as amended.
         -----------------------------------------------------------------------

Item 7.  Identification  and Classification of the Subsidiary Which Acquired
         the Security Being Reported on by the Parent Holding Company or Control
         Person.

     If a parent  holding  company  or Control  person has filed this  schedule,
pursuant to Rule  13d-1(b)(1)(ii)(G),  so indicate under Item 3(g) and attach an
exhibit  stating the  identity  and the Item 3  classification  of the  relevant
subsidiary.  If a parent  holding  company  or  control  person  has filed  this
schedule  pursuant to Rule 13d-1(c) or Rule 13d-1(d),  attach an exhibit stating
the identification of the relevant subsidiary.

            Not applicable.
         -----------------------------------------------------------------------

Item 8.  Identification  and  Classification  of Members of the Group.

     If a group has filed this schedule  pursuant to  ss.240.13d-1(b)(1)(ii)(J),
so indicate under Item 3(j) and attach an exhibit  stating the identity and Item
3 classification of each member of the group. If a group has filed this schedule
pursuant to  ss.240.13d-1(c) or  ss.240.13d-1(d),  attach an exhibit stating the
identity of each member of the group.

            Not applicable.
         -----------------------------------------------------------------------

Item 9.  Notice of Dissolution of Group.

     Notice of dissolution of a group may be furnished as an exhibit stating the
date  of  the   dissolution  and  that  all  further  filings  with  respect  to
transactions in the security reported on will be filed, if required,  by members
of the group, in their individual capacity. See Item 5.

            Not applicable.
          ----------------------------------------------------------------------

Item 10.  Certification.

          By  signing  below I certify  that,  to the best of my  knowledge  and
          belief, the securities referred to above were not acquired and are not
          held for the purpose of or with the effect of changing or  influencing
          the control of the issuer of the  securities and were not acquired and
          are not held in connection with or as a participant in any transaction
          having such purpose or effect.



                                    SIGNATURE

     After  reasonable  inquiry and to the best of my  knowledge  and belief,  I
certify that the information  set forth in this statement is true,  complete and
correct.


Date: February 11, 2005
                                    /s/ Ahmet H. Okumus# **
                                    -----------------------------
                                        Ahmet H. Okumus

#  The Reporting Person affirmatively  disclaims being a "group" for purposes of
   Section 16 of the Securities Exchange Act of 1934, as amended, with any of Of
   the entities identified in Item 6 above.

** The  Reporting  Persons  disclaim  beneficial  ownership in the Common Stock,
   except to the extent of their pecuniary interest therein.

The  original  statement  shall be signed by each  person  on whose  behalf  the
statement is filed or his authorized representative.  If the statement is signed
on behalf of a person by his authorized  representative  other than an executive
officer  or   general   partner  of  the   filing   person,   evidence   of  the
representative's  authority to sign on behalf of such person shall be filed with
this statement,  provided,  however, that a power of attorney,  for this purpose
which is already on file with the Commission may be  incorporated  by reference.
The name and any title of each person who signs the statement  shall be typed or
printed beneath his signature.

Note.  Schedules  filed in paper format shall include a signed original and five
copies of the  schedule,  including  all  exhibits.  See  s.240.13d-7  for other
parties for whom copies are to be sent.

Attention.  Intentional  misstatements  or omissions of fact constitute  federal
criminal violations (see 18 U.S.C. 1001).


21952.0001 #546603