Exhibit 10.20I

Pages where confidential treatment has been requested are stamped “Confidential
Treatment Requested and

the Redacted Material has been separately filed with the Commission,” and places
where information has

been redacted have been marked with (***).

THIRTEENTH AMENDMENT

TO

CSG MASTER SUBSCRIBER MANAGEMENT SYSTEM AGREEMENT

BETWEEN

CSG SYSTEMS, INC.

AND

COMCAST CABLE COMMUNICATIONS MANAGEMENT, LLC

This Thirteenth Amendment (the “Amendment”) is made by and between CSG Systems,
Inc., a Delaware corporation (“CSG”) and Comcast Cable Communications
Management, LLC, a Delaware Limited Liability Company (“Customer”). CSG and
Customer entered into a certain CSG Master Subscriber Management System
Agreement dated March 17, 2004 (the “Agreement”), and now desire to amend the
Agreement in accordance with the terms and conditions set forth in this
Amendment. If the terms and conditions set forth in this Amendment shall be in
conflict with the Agreement, the terms and conditions of this Amendment shall
control. Any terms in initial capital letters or all capital letters used as a
defined term but not defined in this Amendment shall have the meaning set forth
in the Agreement. Upon execution of this Amendment by the parties, any
subsequent reference to the Agreement between the parties shall mean the
Agreement as amended by this Amendment. Except as amended by this Amendment, the
terms and conditions set forth in the Agreement shall continue in full force and
effect according to their terms.

CSG and Customer agree to the following as of the Effective Date:

 

1. Customer desires to add Full Color processing to the Direct Solutions (print
and mail) fees; therefore, Schedule F, Section III.A.II under CSG SERVICES shall
be amended to include the following fee for Full Color processing:

 

Description of Item/Unit of Measure

   Frequency    Fee

E.     Full Color Processing – Front and/or Back Side of Each Physical Page
(Note 18)

     

•        * – *,***,*** ******* ******** ***** *** *****

   ********
****    $*.****

•        *,***,*** – **,***,*** ******* ******** ***** *** *****

   ********
****    $*.****

•        **,***,*** – **,***,*** ******* ******** ***** *** *****

   ********
****    $*.****

•        **,***,*** – **,***,*** ******* ******** ***** *** *****

   ********
****    $*.****

•        **,***,*** * ******* ******** ***** *** *****

   ********
****    $*.****

F.     Full Color Processing – Ad Pages (Note 19)

   ******* ****    *****

Note 18: Full Color is available on both sides of each physical statement page.
*** *** ***** ** ******** ******* ********’* ***** ******** **** ***** ** *
******* ***** ********** ** *** ****** ****** ** ******** ***** **** ********
***** ********** (*.*. *** *** ** ******** ******* *** ******** **** ********
***** ** ***) “**** ***** ********** ***”. The parties agree to execute a
separate Statement of Work (“SOW”) for the development and implementation of
Full Color ***** *** ******** #*******.

Note 19: *** ************* ******** *** ******* **** ********** ****** ** ***
***** *** ** ***** *** *****/***** ***** **********, ***** ** ********* **
******** * ** **** *********. **** ********* ** ******** ********** ** ****
***** **********, **** ***** ** **** ******* ***** ** ******** ******** ** ****
******* *., ***** **** ****** ****** ** ********.

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

2. ******** ***** ** ******* ** *** ********* ******** ******** (*** “*******
**********”) ********** ** **** ***** **********:

 

•        ****/**** ******** **** **** ***** ********** ***** (************

** *** ******** ******* ******** **, ****)

   $*,***,***

•        **** ******** **** **** ***** ********** ***** (******** **, ****

******* ******** **, ****)

   $*,***,***

•        **** ******** **** **** ***** ********** ***** (******** **, ****

******* ******** **, ****)

   $***,***

************ ** *** ******* ********** ***** ** ********** ** *** ******** ***
****** ****** ******* *** *** **** ***** ********** *** ** ******* ** *********
* ***** *** *** ********** ******** **** ******. ** ********, ** *** ***** ***
********** **** ******* ***** *****/***** ***** ********** ** ******** **
********* * *****, **** “********” **** ***** ********** *** ******* ***** ****
** **** *** ******** ** ********** *** ******* **********. ** *** ***** ***
******* ********** ******* *** ****** ****** ****** ********* *** “********”
**** ***** ********** *** *** ********** ******* ***** *****/***** *****
********** ** ******* ** ********* *, *** ***** ****** *** ******* ******* **
********* * ***** *** *** ******** *********** ******. ** *** ***** ******** **
***** ***** ** *** ******* **********, **** *** ***** ******* ******** ***
****** ******** ** **** *** ******* **********. ** *** ***** ********’* ******
****** ******, ********* *** “********” **** ***** ********** *** *** **********
******* ***** *****/***** ***** ********** ** ******* ** ********* *, *******
*** ******* **********, **** *** ****** ** ***** *** ****** ****** ******
********* *** “********” **** ***** ********** *** *** ********** ******* *****
*****/***** ***** ********** ** ******* ** ********* *, ******* *** *******
********** **** ** **** ** **** ******* *** ******* ********** ** *** *********
******** **** ******. All invoices shall be paid in accordance with the payment
terms set forth in the Agreement. For clarity, the following examples are
offered:

 

  a) ****** *** ******** ****** ****/****, ******** ** ******** $*,***,*** **
****** **** ***** ********** ****. *** ******* ********** ** $*,***,*** *** ***
***** ** ******** ** ******* ******** ** ********** $***,*** ***** ***** **
******** **/**/****.

 

  b) ****** *** ******** ****** ****/****, ******** ** ******** $*,***,*** **
****** **** ***** ********** ****. *** ******* ********** ** $*,***,***.
********’* ******* ********** *** *** **** ******** **** ****** ***** ** *******
** $***,*** ** $*,***,***. ********’* ****** **** ***** ********** **** ** ***
**** ******** **** ****** **** $*,***,***. *** ***** ** ******** ** *******
******** ** ********** $***,*** ***** ***** ** ******** **/**/****.

 

3.

***’* ******* ****** *** ******* ******** ** *** **** ** *** ******** *****
******* *** **** ** *** ******* *****. ****, *** ******** **, **** ******* ****
********* *** ******** ********* **** ******** **, **** ******* ******** **,
****. ** *** ***** *** *** ***** ** *** **** ***** ********** **** *** ***
********** ******* *** ***** ** ********* * ***** *** *** ********** ** **** ***
******* ********** *** *** ********** ******, *** ***** ********* *** ******
****** ** ********* ***** **** **** ******* **** **** ***** *** *** ****** ****
******** **** ******* ******** **** ** *** ********** ****** (“********
***********”), ********* *** **** ***** ********** **** *** **** ********* ****
****** *** ******* **** ****** ** ** ** *** **** ******** ** ******** ***
******** ** *********** ** ******** *** *** ******* ********** *** ***
********** ******. *******, ** *** ***** ** ********* * *****, ** ** ********
*********** ****** *** *** ** ******** ********** ***** ***** ***** *****
********** ** *** **** ****** *** ******** *********** ****** ******** **
********* * *****, *** ***** ******* *** ******* **** ***** **** **** ********
*** ***** ********** ******* ***** *****/***** ***** ********** *** ****
“********” ******* **** ** ******** *** ******** ** *********** ** ******** ***
********* *** ******* **********. *******, ** *** ******** *********** **
*********, *** ******* **** ** *** ******** *********** ** **** *** *****
*******’ ******* ********** **** *** ** ******** *** ********* ** ***
*********** ** ********* ** *** ******* ********** ** *** ** *** ************
********** ******.

 

4.

** ************* ** *** ********* **** ***** **********, ******** ****** ****
*** ***** ******** ** ** *** ********* ******** ** ***** *** **** ******** ***
********* ***********, ***** *****

 

   Page 2 of 3    4/28/08

CONFIDENTIAL AND PROPRIETARY INFORMATION - FOR USE BY AUTHORIZED EMPLOYEES OF
THE PARTIES HERETO ONLY AND IS NOT FOR GENERAL DISTRIBUTION WITHIN OR OUTSIDE
THEIR RESPECTIVE COMPANIES

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

 

**** ******* ***** ********* *********** *** ***** *** ******** *** ********,
*** *** ******** ** *** *********. ** *** ***** *** ********* ******* ** **
********** ***** ** ***** ******* ** *** ******* ********** ******** ** *******
* ** **** *********, ******** ****** ** ** ****** *** *** *** *********** ******
***** ******* **********.

 

5. ******** **** ****** **** *** ***** ******* ****** **** *** ******** *.
******** *********** ********* *** ******** ** ** ******* ** ********** *. (**)
******** ********* ******* ** *** ***** *** ****** ********* ***** ********
***** ******* ********** **** ****** ** ****** ** ******* ******* (***) ** ***
***** ******* ********* ****** *** **** *****. *** **** ******, *** ***** **
******** ** ** ********** *********** (**) ***** ** ******* **** ***** *** **
********** *********** (**) ***** ** ******* *** ***** ****** ***********
********* *** ******** *****. ** ** *******, ** ********’* ****** *********
***** ** *** ***** *** ***,*** ******* ********** **** ***,*** *******
********** ********* *****, ********* ********** ********* **** ****** ** **.**%
** ***** ******* ********* ****** *** **** ***** (***,*** ******* ** ***,***).
*********, *** ***** ** ******** ** * ***** ** ***** ******** **** ****
*********** (**) ***** ** ******* *** ****** ********* ***** ** **** ** **
********** *********** (**) ***** ** ******* **** ** *** *****, ****** *** *****
********* ****** ********** ** *** ******* *** ***** ******. ** * ***** **
*************, ** ** ***** **** *** *********** ******** *** ********* *******
*** *** ********** ***** ** ******** **** **** *********** (**) *****.

 

6. ******** ************ **** *** ******* ******* (****) ** ********’* *******
********* ******, *** ********’* *********** ********** ** ***’* *******
********, **** ** ******** *** ** *** *** ********** ********. *******, ******
** ***** ******* ********** ** ***’* ******** ******** ****, ** ** *** ***** **
** ********** ** ********* ****** **** ********* ******** ** **** ***** ***
***** ***’* ********** **** ******** *, *********** ********* *** ******** ** **
******* ** ********** *. (**) ******** ********* *******, ******** ************
*** ****** **** ****** **** ******, ********** **** ** ******* ***** *****/*****
***** **********. ******** ***** *** ** ******* *** **** ***** ********** ***
*** *** ********** ******* ***** *****/***** ***** **********. *******, ***
******** ** ********** *** ******* **********, *** ***** ******* *** **** *****
********** *** ******* **** ***** **** **** ******** *** ***** ********** ****
**** ******* ***** *****/***** ***** ********** *** **** “********” **** *****
********** *** ******* **** ** ******** *** ******** ** *********** ** ********
*** ********* *** ******* **********.

 

7. The parties acknowledge and agree that, as at the date of execution of this
Amendment, they have initiated negotiations for the purpose of amending and
restating the Agreement (the “2008 Agreement”). The parties intend that the
terms of the 2008 Agreement shall supersede and replace the terms of the
Agreement.

IN WITNESS WHEREOF, the parties execute this Amendment on the date last signed
below (“Effective Date”).

 

COMCAST CABLE COMMUNICATIONS

MANAGEMENT, LLC (“CUSTOMER”)

    CSG SYSTEMS, INC. (“CSG”) By:   /s/ Andrew J. Baer     By:   /s/ Peter E.
Kalan Name:   Andrew J. Baer     Name:   Peter E. Kalan Title:   SVP & CIO    
Title:   CEO Date:   May 22, 2008     Date:   May 29, 2008

 

   Page 3 of 3    4/28/08

CONFIDENTIAL AND PROPRIETARY INFORMATION - FOR USE BY AUTHORIZED EMPLOYEES OF
THE PARTIES HERETO ONLY AND IS NOT FOR GENERAL DISTRIBUTION WITHIN OR OUTSIDE
THEIR RESPECTIVE COMPANIES