Second Amendment to Loan Agreement and Promissory Note            
Exhibit: 10.6.3

      This Second Amendment to the Loan Agreement and Promissory Note is dated
May 8, 2001 and entered into by and between Clayton A. Thomas, Jr. (“Borrower”)
and Net2000 Communications Group, Inc. (“Company”).

      WHEREAS, Borrower and Company entered into a letter agreement (“Loan
Agreement”) dated December 5, 2000 and amended on February 1, 2001 in which the
Company agreed to lend Borrower an aggregate principal amount of up to
$1,500,000 (collectively, the “Loan”); and

      WHEREAS, the obligation of the Borrower to repay the Loan was evidenced by
a Promissory Note (“Note”) dated December 5, 2000 and amended as of February 1,
2001 and signed by Borrower;

      WHEREAS, under the current terms of the Note, the Borrower is obligated to
pay to the Company monthly interest on the outstanding principal balance of the
Loan at the Applicable Federal Rate (“Interest Rate”) and repay the outstanding
balance of the Loan in full on the Maturity Date (as defined in the amended Loan
Agreement);

      WHEREAS, the parties wish to further amend the Loan Agreement and the
Note;

      NOW, THEREFORE, the parties agree as follows:

1.    The first sentence of Paragraph 1 of the Loan Agreement is amended by
deleting “June 6, 2001” and replacing it with “May 31, 2002”.

2.    Paragraph 2 of the Loan Agreement is deleted in its entirety and replaced
with the following sentence:

      “Subject to the terms and conditions of this letter (herein referred to as
this “Agreement”), the Borrower may prepay this Loan and/or any accrued but
unpaid interest in whole or in part at any time without penalty or premium.”

3.    Paragraph 5(a) of the Loan Agreement is deleted in its entirety and
Paragraph 5(b) is hereby renumbered as Paragraph 5(a).

4.    The following new Paragraph 5(b) is hereby included in the Loan Agreement:

      "(b) The Company hereby waives repayment of the first one hundred thousand
dollars ($100,000.00) of the outstanding balance of the Loan (“Loan Waiver”) and
such Loan Waiver shall be subject to a tax true up whereby the Loan Waiver
amount will be grossed up based on Borrower’s income tax bracket so that it is a
net waiver amount and the Company will pay Borrower such additional compensation
as is

 

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      necessary to place Borrower in the same after tax position he would have
been in had no income tax been incurred on the Loan Waiver.”

5.    Paragraph 2 of the Note, which was deleted in its entirety and replaced
with a new Paragraph 2 pursuant to the First Amendment as of February 1, 2001,
is further amended by deleting the phrase “and shall be paid currently in cash
on a monthly basis on each Payment Date (as defined below)” from the first
sentence of Paragraph 2. The further amended version of Paragraph 2 shall be as
follows:

      “Interest Rate Provisions. Except as provided in Section 2.2 hereof, from
the date hereof and thereafter until the outstanding amount hereof is paid in
full, interest shall accrue on the principal balance of this Note outstanding
from time to time at the Applicable Federal Rate (“AFR”) in effect at the end of
each month as published by the United States Internal Revenue Service (“Interest
Rate”). Each change in any interest rate provided for herein based upon the AFR
resulting from a change in the AFR shall take effect without notice to the
Borrower at the time of such change in the AFR.”

6.    Paragraph 2.2 of the Note is amended by deleting the phrase “on each
Payment Date (as defined below)”.

7.    Paragraph 3.1 of the Note is deleted in its entirety and replaced with the
following new Paragraph 3.1:

      “3.1(a) Accrued Interest: Commencing on the last day of the calendar month
following the date the initial advance of the Loan is made and continuing on the
last day of each succeeding calendar month thereafter, the Borrower shall accrue
interest at the applicable Interest Rate on the then outstanding principal
balance under this Note.”

8.    Paragraph 3.3 of the Note is amended by inserting the phrase “and/or any
accrued interest” between the words “Note” and “in”.

9.    All other terms, conditions, and obligations of the Loan Agreement and
Promissory Note shall remain in full force and effect unless amended in writing
and signed by both parties.

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      IN WITNESS WHEREOF, the parties hereto have caused this Second Amendment
to the Loan Agreement and Promissory Note to be duly executed and effective as
of May 8, 2001.

      NET2000 COMMUNICATIONS GROUP, INC         /s/ Clayton A. Thomas Jr.
CLAYTON A. THOMAS, JR.,
     AS BORROWER   BY:/s/ Donald Clarke          Donald Clarke
      Chief Financial Officer

    COMMONWEALTH OF VIRGINIA ) ) ss: COUNTY OF FAIRFAX )

      On this 17 day of July, 2001 before me personally appeared CLAYTON A.
THOMAS, JR., to be known to be the person who executed the foregoing instrument
and who being by me duly sworn, did depose and say that he signed his name to
the foregoing instrument.

       /s/ Catherine Riehn            
NOTARY PUBLIC

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