Exhibit 10.3

AMENDMENT NO. 4

TO

REGISTRATION RIGHTS AGREEMENT

AMENDMENT NO. 4 TO REGISTRATION RIGHTS AGREEMENT (this “Amendment”), dated as of
May 13, 2008, made among ITC^DeltaCom, Inc., a Delaware corporation (the
“Company”), and each person listed on the signature pages hereof under the
heading “WCAS Securityholders.”

WITNESSETH:

WHEREAS, the parties to this Amendment wish to amend the Registration Rights
Agreement, dated as of October 6, 2003 and amended as of December 4,
2003, July 26, 2005 and July 31, 2007 (the “Agreement”), among the Company, the
persons listed on the signature pages thereof under the heading “WCAS
Securityholders” and the other parties to such agreement, as hereinafter set
forth;

NOW, THEREFORE, in consideration of the premises and the mutual covenants and
conditions hereinafter set forth, and for other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged, the parties hereby
agree as follows:

1. Effectiveness. This Amendment shall be effective as of the date set forth in
the preamble of this Amendment.

2. Amendment to Section 1 of Agreement. The definition of “TCP Registration
Rights Agreement” set forth in Section 1 of the Agreement is hereby amended and
restated in its entirety to read as follows:

“TCP Registration Rights Agreement” means the Registration Rights Agreement,
dated as of July 26, 2005, as amended as of July 31, 2007 and May 13, 2008,
among the Company and the other Persons listed on the signature pages thereof.

3. Amendment to Section 15 of Agreement. The second sentence of Section 15 of
the Agreement is hereby amended and replaced in its entirety to read as follows:

“The Holders agree for purposes of this Section 15 that the TCP Registration
Rights Agreement is not inconsistent with the rights of the Holders hereunder.”

4. Miscellaneous. This Amendment shall not constitute an amendment or
modification of any provision of the Agreement not expressly referred to herein.
Except as expressly set forth in this Amendment, the terms, provisions and
conditions of the Agreement shall remain unchanged and in full force and effect.
This Amendment may be executed in counterparts, all of which shall together
constitute a single agreement.

5. GOVERNING LAW. THIS AMENDMENT SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT GIVING EFFECT TO ITS
PRINCIPLES OR RULES OF CONFLICT

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OF LAWS TO THE EXTENT SUCH PRINCIPLES OR RULES WOULD REQUIRE OR PERMIT THE
APPLICATION OF THE LAWS OF ANOTHER JURISDICTION.

 

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IN WITNESS WHEREOF, the parties have executed this Amendment as of the date set
forth in the first paragraph hereof.

 

COMPANY: ITC^DELTACOM, INC. By:  

/s/ J. Thomas Mullis

Name:   J. Thomas Mullis Title:   Senior Vice President – Legal and Regulatory

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WCAS SECURITYHOLDERS: WCAS CAPITAL PARTNERS III, L.P. By:   WCAS CP III
Associates L.L.C., General Partner By:  

/s/ Jonathan M. Rather

Name:   Jonathan M. Rather Title:   Managing Member

WELSH, CARSON, ANDERSON & STOWE VIII, L.P.

By:   WCAS VIII Associates LLC, General Partner By:  

/s/ Jonathan M. Rather

Name:   Jonathan M. Rather Title:   Managing Member

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Individual investors and trusts: By:  

/s/ Jonathan M. Rather

 

Jonathan M. Rather, as Attorney-in-fact

for the individual investors listed below:

  Patrick J. Welsh   Russell L. Carson   Bruce K. Anderson   Andrew M. Paul  
Thomas E. McInerney   Robert A. Minicucci   Anthony J. de Nicola   Paul B.
Queally   D. Scott Mackesy   Sanjay Swani   James Matthews   Laura VanBuren  
Sean Traynor   John Almeida   Eric J. Lee   Jonathan M. Rather   IRA – f/b/o
James Matthews   IRA f/b/o Jonathan M. Rather

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/s/ Jill A. Hanau

Jill A. Hanau Other trusts: The Bruce K. Anderson 2004 Irrevocable Trust By:  

/s/ Mary Anderson

Name:   Mary Anderson Title:   Trustee The Patrick Welsh 2004 Irrevocable Trust
By:  

/s/ Carol A. Welsh

Name:   Carol A. Welsh Title:   Trustee Patrick J. Welsh Tr UA 05 09 05 By:  

/s/ Patrick Welsh

Name:   Patrick Welsh Title:   Trustee