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 (***).

EXHIBIT 10.21A

FIFTH AMENDMENT

TO THE

RESTATED AND AMENDED

CSG MASTER SUBSCRIBER MANAGEMENT SYSTEM AGREEMENT

BETWEEN

CSG SYSTEMS, INC.

AND

COMCAST CABLE COMMUNICATIONS MANAGEMENT, LLC

This FIFTH AMENDMENT (the “Amendment”) is made by and between CSG Systems, Inc.
(“CSG”) and Comcast Cable Communications Management, LLC (“Customer”). The
Effective Date of this Amendment is the date last signed below. CSG and Customer
entered into a certain Restated and Amended CSG Master Subscriber Management
System Agreement (CSG document #2296663) dated July 1, 2008 (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:

 

1. Upon the Effective Date of this Amendment, Schedule F, Fees, Section entitled
CSG Services, Subsection II, Interfaces, Subsection C. High-speed data, is
amended to add the following charge:

 

Description of Item/Unit of Measure

  

Frequency

  

Fee

4.. Non Voice Record Processing

  

************

**********

   *******

 

2. Effective May 1, 2010, Schedule P to the Agreement shall be deleted in its
entirety and replaced with the new Schedule P attached hereto and which is
incorporated herein by this reference.

IN WITNESS WHEREOF the parties hereto have caused this Amendment to be executed
by their duly authorized representatives.

 

COMCAST CABLE COMMUNICATIONS MANAGEMENT, LLC (“CUSTOMER”)     CSG SYSTEMS, INC.
(“CSG”) By:   Andrew J. Baer     By:   /s/ Michael J. Henderson Name:   Andrew
J. Baer     Name:   Michael J. Henderson Title:   SVP & CIO     Title:   EVP
Sales & Marketing Date:   10/21/2010     Date:   10/25/2010

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

*** Confidential Treatment Requested and the Redacted Material has been
separately filed with the Commission.

Schedule P

Customer Authorization Schedule

 

CSG Document

 

Comcast Personnel

 

Title

 

Comment

Master Agreement   ***********   Chief Information Officer   & Amendments  
****************   SVP and Chief Procurement Officer   (and all categories      
Listed below)       SOW / DSOW   *********   SVP Finance & Accounting   Contract
Administration   **********   Vice President, Business Operations   Contract
Administration   ***********   Vice President, Billing Systems   LOA  
****************   Director of Billing   Technical Administrator   ***********  
Vice President, Billing Systems   Contract Administration   **********   Vice
President, Business Operations   Contract Administration   *********   SVP
Finance & Accounting     ***********   Director of Billing Systems   SRF  
****************   Director of Billing   Technical Administrator   ***********  
Director of Billing Systems     ***********   Vice President, Billing Systems  
  **********   Vice President, Business Operations     *********   SVP Finance &
Accounting   IPA   ***********   Director of Billing Systems     ***********  
Vice President, Billing Systems   BRD   ***********   Director of Billing
Systems     ***********   Vice President, Billing Systems   Billing Disputes  
*********   SVP Finance & Accounting     ***********   Vice President, Billing
Systems     ************   Manager Finance  

 

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CONFIDENTIAL AND PROPRIETARY INFORMATION - FOR USE BY AUTHORIZED EMPLOYEES FOR
THE PARTIES

HERETO ONLY AND IS NOT FOR GENERAL DISTRIBUTION WITHIN OR OUTSIDE THEIR
RESPECTIVE COMPANIES