**Exhibit 4.3.1**

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[REUTERS LIMITED LETTERHEAD]

22 October 2004

SAVVIS Communications Corporation1285 Worldgate DriveHerndon, VA 20170Attn: Executive Vice President, StrategicDevelopment

Re:      Network      Services Agreement

Ladies and Gentlemen:

Reference is made to the Network    Services Agreement by and between Savvis Communications Corporation (“Savvis”)    and Reuters Limited (“Reuters”), dated as of September 28, 2001    (together with subsequent amendments thereto, the “Agreement”).    The purpose of this letter is to set forth the parties’ agreement regarding    any credits, payments or offsets, including but not limited to those against    Domestic or International MMCs, due as a result of Reuters’ making    of any Bankruptcy Payments, as provided in Sections 3.6.2, 3.6.7 and 11.2    of the Agreement. The Parties intend by this Agreement to compromise, settle,    resolve and discharge all claims, contracts and liabilities between them    regarding the Bankruptcy Payments or any credits arguably due as a result    of Bankruptcy Payments upon the terms and conditions hereinafter set forth    in order to avoid further expense, inconvenience and unnecessary litigation    without any admission, assumption or finding of liability by or against either    Party. Capitalized terms used, but not defined, herein shall have the meaning    set forth in the Agreement.

Notwithstanding anything in the Agreement    to the contrary, as the sole result of Reuters’ making any Bankruptcy    Payments, the Domestic MMC shall be adjusted as follows: 

a)      All    MMC obligations shall cease as of October 1, 2005.

b)      Reuters    will receive a monthly credit against its Domestic Shortfall Payment obligation    for each month from January 1, 2005 through September 30, 2005 equal to the    greater of (i) $388,889 and (ii) 60% of the Domestic Shortfall Payment for    such month *provided that*such credit(s) shall never exceed $667,667    in any single month or $6 million in the aggregate. For the avoidance of    doubt, the preceding does not affect the calculation of the Domestic Monthly    Spend, but only the amount of the Domestic Shortfall Payment that Reuters    is required to pay to Savvis

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In consideration for the credits    specified herein, Reuters on behalf of itself and all affiliates waives its    right to make any further claim for Bankruptcy Payments, or to obtain any    further payment, credit or offsets for Bankruptcy Payments, and Savvis, on    behalf of itself and all affiliates, waives its right to claim that any Bankruptcy    Payments credits or offsets agreed to herein were improperly paid to Reuters    or to obtain any refund of such. Please sign and return both copies of this    letter to confirm your acceptance of the above. One copy will be returned    to you in due course for your records.

|   | Verytruly yours, |
|--------|------------------|
|   |             |   |
|   | Reuters Limited  |
|   |             |   |
|   |             |   |
|   | By:              | /s/ Barry Woodward |
|   |             | Name: Barry Woodward |
|   |             | Title: Head of Infrastructure Development & Networking |

Accepted as of the day and year firstabove written:

SAVVIS Communications Corporation

|   |                       |
|--------|----------------------------|
| By:    | /s/ Grier C. Raclin        |
|   | Name: Grier C. Raclin      |
|   | Title: Chief Legal Officer |
|   | Date: October 25, 2004     |

 

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